Terminal device, base station device, communication method, and integrated circuit

ABSTRACT

A terminal device transmits an RI determined by the terminal device, the RI corresponding to PDSCH transmission and corresponding to the number of layers, transmits capability information including first information, second information, third information, and/or fourth information, and receives fifth information, wherein the first information indicates a UE category corresponding to a first maximum number of the layers, the second information indicates a first bandwidth class, the third information indicates a second maximum number of the layers, the fourth information indicates a third maximum number of the layers, the fifth information indicates a fourth maximum number of the layers, and a fifth maximum number of the layers assumed for determining a bit width for the RI is given by referring to any one of the first maximum number of the layers, the second maximum number of the layers, and the fourth maximum number of the layers.

TECHNICAL FIELD

The present invention relates to a terminal device, a base stationdevice, a communication method, and an integrated circuit.

The present application claims priority based on JP 2015-133998 filed onJul. 3, 2015, the contents of which are incorporated herein.

BACKGROUND ART

In the 3rd Generation Partnership Project (3GPP), a radio access methodand a radio network for cellular mobile communications (hereinafter,referred to as “Long Term Evolution (LTE)”, or “Evolved UniversalTerrestrial Radio Access (EUTRA)”) have been studied. In LTE, a basestation device is also referred to as evolved NodeB (eNodeB), and aterminal device is also referred to as User Equipment (UE). LTE is acellular communication system in which an area is divided into multiplecells to form a cellular pattern, the area being served by a basestation device. A single base station device may manage a plurality ofcells.

In LTE, carrier aggregation in which a terminal device communicates witha base station device through a plurality of carriers (cells)aggregated, and Multiple Input Multiple Output (MIMO) in which aplurality of layers are spatial-multiplexed, have been introduced. TheMIMO has been introduced since LTE Release 8, and the carrieraggregation has been introduced since LTE Release 10 (NPLs 2, 3, and 4).

In LTE, functions of the MIMO and the carrier aggregation have beencontinuously extended, even after the introduction of the MIMO and thecarrier aggregation. A terminal device transmits, to a base stationdevice, capability information indicating the technology of the MIMO andthe carrier aggregation supported by the terminal device (NPL 5).

CITATION LIST Non-Patent Literature

-   NPL 1: “3GPP TS 36.101 V12.7.0 (2015-03)”, 2 Apr. 2015.-   NPL 2: “3GPP TS 36.211 V12.5.0 (2015-03)”, 26 Mar. 2015.-   NPL 3: “3GPP TS 36.212 V12.4.0 (2015-03)”, 26 Mar. 2015.-   NPL 4: “3GPP TS 36.213 V12.5.0 (2015-03)”, 26 Mar. 2015.-   NPL 5: “3GPP TS 36.306 V12.4.0 (2015-03)”, 27 Mar. 2015.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, in the above-described radio systems, an actual operation of abase station device and an operation of the base station device assumedby a terminal device may be different, and thus, the base station deviceand the terminal device sometimes may not correctly communicate witheach other. For example, there is a possibility that an actual operationof the base station device and an operation of the base station deviceassumed by the terminal device and/or an actual operation of theterminal device and an operation of the terminal device assumed by thebase station device are different with respect to a bit width of a RankIndicator (RI) fed back by the terminal device to the base stationdevice, a rate matching of a code block of a downlink transport block,storing of soft channel bits, and the like.

The present invention has been made in light of the foregoing, and anobject of the present invention is to provide a terminal device capableof efficiently communicating with a base station device, a base stationdevice, a communication method, and an integrated circuit.

Means for Solving the Problems

(1) In order to accomplish the object described above, aspects of thepresent invention are contrived to provide the following means. That is,a first aspect of the present invention is a terminal device, including:a transmission unit configured to transmit a Rank Indicator (RI)determined by the terminal device, the RI corresponding to PhysicalDownlink Shared CHannel (PDSCH) transmission in a first downlinkcomponent carrier corresponding to a first bandwidth class of a firstband in a first band combination and corresponding to the number ofuseful layers; and a reception unit configured to receive the PDSCH. Thetransmission unit transmits capability information including firstinformation, second information, and/or third information, and thereception unit receives fifth information for the first downlinkcomponent carrier corresponding to the first bandwidth class of thefirst band in the first band combination. The first informationindicates a UE category corresponding to a first maximum number of thelayers supported by the terminal device in a downlink; the secondinformation indicates the first bandwidth class being for the first bandin the first band combination and corresponding to the number ofdownlink component carriers supported by the terminal device; the thirdinformation is applied to all of one or more downlink component carrierscorresponding to the first bandwidth class of the first band in thefirst band combination, and indicates a second maximum number of thelayers supported by the terminal device in the downlink; and the fifthinformation indicates a fourth maximum number of the layers. In a casethat the fifth information for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured, a fifth maximum number of thelayers assumed for determining a bit width for the RI is given byreferring to any one of the first information and the third information.In a case that the fifth information for the first downlink componentcarrier corresponding to the first bandwidth class of the first band inthe first band combination is configured, the fifth maximum number ofthe layers assumed for determining the bit width for the RI is given byreferring to the fifth information.

(2) A second aspect of the present invention is a base station device,including: a reception unit configured to receive, from a terminaldevice, a Rank Indicator (RI) determined by the terminal device, the RIcorresponding to Physical Downlink Shared CHannel (PDSCH) transmissionin a first downlink component carrier corresponding to a first bandwidthclass of a first band in a first band combination and corresponding tothe number of useful layers; and a transmission unit configured totransmit the PDSCH to the terminal device. The reception unit receives,from the terminal device, capability information including firstinformation, second information, and/or third information, and thetransmission unit transmits, to the terminal device, fifth informationfor the first downlink component carrier corresponding to the firstbandwidth class of the first band in the first band combination. Thefirst information indicates a UE category corresponding to a firstmaximum number of the layers supported by the terminal device in adownlink; the second information indicates the first bandwidth classbeing for the first band in the first band combination and correspondingto the number of downlink component carriers supported by the terminaldevice; the third information is applied to all of one or more downlinkcomponent carriers corresponding to the first bandwidth class of thefirst band in the first band combination, and indicates a second maximumnumber of the layers supported by the terminal device in the downlink;and the fifth information indicates a fourth maximum number of thelayers. In a case that the fifth information for the first downlinkcomponent carrier corresponding to the first bandwidth class of thefirst band in the first band combination is not configured for theterminal device, a fifth maximum number of the layers assumed fordetermining a bit width for the RI is given by referring to any one ofthe first information and the third information. In a case that thefifth information for the first downlink component carrier correspondingto the first bandwidth class of the first band in the first bandcombination is configured for the terminal device, the fifth maximumnumber of the layers assumed for determining the bit width for the RI isgiven by referring to the fifth information.

(3) A third aspect of the present invention is a communication methodused for a terminal device, the method including the steps of:transmitting a Rank Indicator (RI) determined by the terminal device,the RI corresponding to Physical Downlink Shared CHannel (PDSCH)transmission in a first downlink component carrier corresponding to afirst bandwidth class of a first band in a first band combination andcorresponding to the number of useful layers; receiving the PDSCH;transmitting capability information including first information, secondinformation, and/or third information; and receiving fifth informationfor the first downlink component carrier corresponding to the firstbandwidth class of the first band in the first band combination. Thefirst information indicates a UE category corresponding to a firstmaximum number of the layers supported by the terminal device in adownlink; the second information indicates the first bandwidth classbeing for the first band in the first band combination and correspondingto the number of downlink component carriers supported by the terminaldevice; the third information is applied to all of one or more downlinkcomponent carriers corresponding to the first bandwidth class of thefirst band in the first band combination, and indicates a second maximumnumber of the layers supported by the terminal device in the downlink;and the fifth information indicates a fourth maximum number of thelayers. In a case that the fifth information for the first downlinkcomponent carrier corresponding to the first bandwidth class of thefirst band in the first band combination is not configured, a fifthmaximum number of the layers assumed for determining a bit width for theRI is given by referring to any one of the first information and thethird information. In a case that the fifth information for the firstdownlink component carrier corresponding to the first bandwidth class ofthe first band in the first band combination is configured, the fifthmaximum number of the layers assumed for determining the bit width forthe RI is given by referring to the fifth information.

(4) A fourth aspect of the present invention is a communication methodused for a base station device, the method including the steps of:receiving, from a terminal device, a Rank Indicator (RI) determined bythe terminal device, the RI corresponding to Physical Downlink SharedCHannel (PDSCH) transmission in a first downlink component carriercorresponding to a first bandwidth class of a first band in a first bandcombination and corresponding to the number of useful layers;transmitting the PDSCH to the terminal device; receiving, from theterminal device, capability information including first information,second information, and/or third information; and transmitting, to theterminal device, fifth information for the first downlink componentcarrier corresponding to the first bandwidth class of the first band inthe first band combination. The first information indicates a UEcategory corresponding to a first maximum number of the layers supportedby the terminal device in a downlink; the second information indicatesthe first bandwidth class being for the first band in the first bandcombination and corresponding to the number of downlink componentcarriers supported by the terminal device; the third information isapplied to all of one or more downlink component carriers correspondingto the first bandwidth class of the first band in the first bandcombination, and indicates a second maximum number of the layerssupported by the terminal device in the downlink; and the fifthinformation indicates a fourth maximum number of the layers. In a casethat the fifth information for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured for the terminal device, afifth maximum number of the layers assumed for determining a bit widthfor the RI is given by referring to any one of the first information andthe third information. In a case that the fifth information for thefirst downlink component carrier corresponding to the first bandwidthclass of the first band in the first band combination is configured forthe terminal device, the fifth maximum number of the layers assumed fordetermining the bit width for the RI is given by referring to the fifthinformation.

(5) A fifth aspect of the present invention is an integrated circuitcausing a terminal device to exhibit a series of functions including thefunctions of: transmitting a Rank Indicator (RI) determined by theterminal device, the RI corresponding to Physical Downlink SharedCHannel (PDSCH) transmission in a first downlink component carriercorresponding to a first bandwidth class of a first band in a first bandcombination and corresponding to the number of useful layers; receivingthe PDSCH; transmitting capability information including firstinformation, second information, and/or third information; and receivingfifth information for the first downlink component carrier correspondingto the first bandwidth class of the first band in the first bandcombination. The first information indicates a UE category correspondingto a first maximum number of the layers supported by the terminal devicein a downlink; the second information indicates the first bandwidthclass being for the first band in the first band combination andcorresponding to the number of downlink component carriers supported bythe terminal device; the third information is applied to all of one ormore downlink component carriers corresponding to the first bandwidthclass of the first band in the first band combination, and indicates asecond maximum number of the layers supported by the terminal device inthe downlink; and the fifth information indicates a fourth maximumnumber of the layers. In a case that the fifth information for the firstdownlink component carrier corresponding to the first bandwidth class ofthe first band in the first band combination is not configured, a fifthmaximum number of the layers assumed for determining a bit width for theRI is given by referring to any one of the first information and thethird information. In a case that the fifth information for the firstdownlink component carrier corresponding to the first bandwidth class ofthe first band in the first band combination is configured, the fifthmaximum number of the layers assumed for determining the bit width forthe RI is given by referring to the fifth information.

(6) A fifth aspect of the present invention is an integrated circuitcausing a base station device to exhibit a series of functions includingthe functions of: receiving, from a terminal device, a Rank Indicator(RI) determined by the terminal device, the RI corresponding to PhysicalDownlink Shared CHannel (PDSCH) transmission in a first downlinkcomponent carrier corresponding to a first bandwidth class of a firstband in a first band combination and corresponding to the number ofuseful layers; transmitting the PDSCH to the terminal device; receiving,from the terminal device, capability information including firstinformation, second information, and/or third information; transmitting,from the terminal device, fifth information for the first downlinkcomponent carrier corresponding to the first bandwidth class of thefirst band in the first band combination. The first informationindicates a UE category corresponding to a first maximum number of thelayers supported by the terminal device in a downlink; the secondinformation indicates the first bandwidth class being for the first bandin the first band combination and corresponding to the number ofdownlink component carriers supported by the terminal device; the thirdinformation is applied to all of one or more downlink component carrierscorresponding to the first bandwidth class of the first band in thefirst band combination, and indicates a second maximum number of thelayers supported by the terminal device in the downlink; and the fifthinformation indicates a fourth maximum number of the layers. In a casethat the fifth information for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured for the terminal device, afifth maximum number of the layers assumed for determining a bit widthfor the RI is given by referring to any one of the first information andthe third information. In a case that the fifth information for thefirst downlink component carrier corresponding to the first bandwidthclass of the first band in the first band combination is configured forthe terminal device, the fifth maximum number of the layers assumed fordetermining the bit width for the RI is given by referring to the fifthinformation.

Effects of the Invention

According to the aspects of the present invention, a terminal device anda base station device can efficiently communicate with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram of a radio communication system accordingto the present embodiment.

FIG. 2 is a diagram illustrating a schematic configuration of a radioframe according to the present embodiment.

FIG. 3 is a diagram illustrating a configuration of a slot according tothe present embodiment.

FIG. 4 is a schematic block diagram illustrating a configuration of aterminal device 1 according to the present embodiment.

FIG. 5 is a schematic block diagram illustrating a configuration of abase station device 3 according to the present embodiment.

FIG. 6 is a diagram illustrating one example of processing in a codingunit 3071 according to the present embodiment.

FIG. 7 is a diagram illustrating one example of processing in amultiplexing unit 3075 according to the present embodiment.

FIG. 8 is a table showing one example of a correspondence of atransmission mode, a DCI format, and a PDSCH transmission schemeaccording to the present embodiment.

FIG. 9 is a table showing one example of a UE category according to thepresent embodiment.

FIG. 10 is a table showing one example of a downlink UE categoryaccording to the present embodiment.

FIG. 11 is a table showing one example of a combination of categoriesindicated by a plurality of capability parameters according to thepresent embodiment.

FIG. 12 is a table showing one example of a bandwidth class according tothe present embodiment.

FIG. 13 is a diagram illustrating one example of a configuration of acapability parameter supportedBandCombination according to the presentembodiment.

FIG. 14 is a diagram illustrating one example of a configuration of thecapability parameter supportedBandCombination according to the presentembodiment.

FIG. 15 is a table showing one example of a combination of the bandwidthclass and a MIMO capability according to the present embodiment.

FIG. 16 is a diagram illustrating one example of a sequence chartbetween the terminal device 1 and the base station device 3 according tothe present embodiment.

FIG. 17 is a diagram illustrating one example of rate matching accordingto the present embodiment.

FIG. 18 illustrates one example of a bit selection and pruning accordingto the present embodiment.

FIG. 19 is a diagram illustrating one example of a flow chart associatedwith a determination of a total number N_(soft) of soft channel bitsaccording to the present embodiment.

FIG. 20 illustrates one example of a method of configuring K_(c)according to the present embodiment.

FIG. 21 is a diagram illustrating one example of a range of <w_(k),w_(k+1), . . . w_((k+nSB−1) mod Ncb)> according to the presentembodiment.

FIG. 22 is a diagram illustrating one example of a flow chart associatedwith a determination of a total number N′_(soft) of the soft channelbits according to the present embodiment.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described.

In the present embodiment, a plurality of cells are configured for aterminal device. A technology in which the terminal device communicatesthrough a plurality of cells is referred to as cell aggregation orcarrier aggregation. The present invention may be applied to each of theplurality of cells configured for the terminal device. Furthermore, thepresent invention may be applied to some of the plurality of configuredcells. Each of the cells configured for the terminal device 1 is alsoreferred to as a serving cell. Any one of Time Division Duplex (TDD)scheme and Frequency Division Duplex (TDD) scheme is applied to eachcell.

The plurality of configured serving cells include one primary cell(PCell) and one or more secondary cells (SCells). The primary cell is aserving cell in which an initial connection establishment procedure hasbeen performed, a serving cell in which a connection re-establishmentprocedure has been started, or a cell indicated as a primary cell duringa handover procedure. The secondary cell may be configured at a point intime when a radio resource control (RRC) connection is established, orlater.

A carrier corresponding to a cell in the downlink is referred to as adownlink component carrier. A carrier corresponding to a cell in theuplink is referred to as an uplink component carrier. The componentcarriers include a transmission bandwidth configuration. For example,the transmission bandwidth configuration is 1.4 MHz, 5 MHz, 10 MHz, 15MHz, or 20 MHz.

FIG. 1 is a conceptual diagram of a radio communication system accordingto the present embodiment. In FIG. 1, the radio communication systemincludes terminal devices 1A to 1C and a base station device 3. Theterminal devices 1A to 1C are each referred to as a terminal device 1,below.

Physical channels and physical signals of the present embodiment will bedescribed.

In FIG. 1, in uplink radio communication from the terminal device 1 tothe base station device 3, the following uplink physical channels areused. The uplink physical channel is used to transmit information outputfrom a higher layer.

-   -   Physical Uplink Control Channel (PUCCH)    -   Physical Uplink Shared Channel (PUSCH)    -   Physical Random Access Channel (PRACH)

The PUCCH is a physical channel that is used to transmit Uplink ControlInformation (UCI). The pieces of uplink control information includedownlink Channel State Information (CSI), a Scheduling Request (SR)indicating a request for a PUSCH resource, and an acknowledgement(ACK)/negative-acknowledgement (NACK) for downlink data (a TransportBlock or a Downlink-Shared Channel (DL-SCH)). The ACK/NACK is alsoreferred to as an HARQ-ACK, HARQ feedback, or response information.

The channel state information includes a Channel Quality Indicator(CQI), a Rank Indicator (RI), and a Precoding Matrix Indicator (PMI).The CQI expresses a combination of a modulation scheme and a coding ratefor a single transport block to be transmitted on the PDSCH. The RIindicates the number of useful layers determined by the terminal device1. The PMI indicates a code book determined by the terminal device 1.The code book is correlated with a precoding of the PDSCH.

The PUSCH is a physical channel that is used to transmit uplink data(Uplink-Shared Channel (UL-SCH)). Furthermore, the PUSCH may be used totransmit the HARQ-ACK and/or channel state information along with theuplink data. Furthermore, the PUSCH may be used to transmit only thechannel state information or to transmit only the HARQ-ACK and thechannel state information.

The PRACH is a physical channel that is used to transmit a random accesspreamble.

In FIG. 1, the following uplink physical signal is used in the uplinkradio communication. The uplink physical signal is not used to transmitinformation output from the higher layer, but is used by a physicallayer.

-   -   Uplink Reference Signal (UL RS)

In the present embodiment, the following two types of uplink referencesignals are used.

-   -   Demodulation Reference Signal (DMRS)    -   Sounding Reference Signal (SRS)

The DMRS is associated with transmission of the PUSCH or the PUCCH. TheSRS has no association with the transmission of the PUSCH or the PUCCH.

In FIG. 1, the following downlink physical channels are used fordownlink radio communication from the base station device 3 to theterminal device 1. The downlink physical channels are used to transmitthe information output from the higher layer.

-   -   Physical Broadcast Channel (PBCH)    -   Physical Control Format Indicator Channel (PCFICH)    -   Physical Hybrid automatic repeat request Indicator Channel        (PHICH)    -   Physical Downlink Control Channel (PDCCH)    -   Enhanced Physical Downlink Control Channel (EPDCCH)    -   Physical Downlink Shared Channel (PDSCH)    -   Physical Multicast Channel (PMCH)

The PBCH is used to broadcast a Master Information Block (MIB), or aBroadcast Channel (BCH), that is shared by the terminal devices 1. TheMIB is transmitted at intervals of 40 ms, and, within the interval, theMIB is repeatedly transmitted every 10 ms. Specifically, initialtransmission of the MIB is performed in a subframe 0 in a radio framethat satisfies SFN mod 4=0, and re-transmission (repetition) of the MIBis performed in subframes 0 in all the other radio frames. A systemframe number (SFN) is a radio frame number. The MIB is systeminformation. For example, the MIB includes information indicating theSFN. The PBCH is transmitted on some or all of the transmit antennaports 0 to 3.

The PCFICH is used to transmit information indicating a region (OFDMsymbols) to be used for transmission of the PDCCH.

The PHICH is used to transmit an HARQ indicator (HARQ feedback orresponse information) indicating an acknowledgement (ACK) or a negativeacknowledgement (NACK) with respect to the uplink data (Uplink SharedChannel (UL-SCH)) received by the base station device 3.

The PDCCH and the EPDCCH are used to transmit Downlink ControlInformation (DCI). The downlink control information is also referred toas a DCI format. The downlink control information includes a downlinkgrant and an uplink grant. The downlink grant is also referred to asdownlink assignment or downlink allocation.

The downlink grant is used for scheduling of a single PDSCH within asingle cell. The downlink grant is used for scheduling of the PDSCHwithin the same subframe as the subframe in which the downlink grant istransmitted. The uplink grant is used for scheduling of a single PUSCHwithin a single cell. The uplink grant is used for scheduling of asingle PUSCH within the fourth or later subframe from the subframe inwhich the uplink grant is transmitted.

A Cyclic Redundancy Check (CRC) parity bits are attached to the DCIformat. The CRC parity bits are scrambled with a Cell-Radio NetworkTemporary Identifier (C-RNTI) or a Semi Persistent Scheduling Cell-RadioNetwork Temporary Identifier (SPS C-RNTI). The C-RNTI and the SPS C-RNTIare identifiers for identifying the terminal device 1 within a cell. TheC-RNTI is used to control the PDSCH or the PUSCH in a single subframe.The SPS C-RNTI is used to periodically allocate a resource for the PDSCHor the PUSCH.

The PDSCH is used to transmit downlink data (Downlink Shared Channel(DL-SCH)).

The PMCH is used to transmit multicast data (Multicast Channel (MCH)).

In FIG. 1, the following downlink physical signals are used in thedownlink radio communication. The downlink physical signals are not usedto transmit the information output from the higher layer, but are usedby the physical layer.

-   -   Synchronization signal (SS)    -   Downlink reference signal (DL RS)

The synchronization signal is used in order for the terminal device 1 tobe synchronized in terms of frequency and time domains for downlink.

The downlink reference signal is used in order for the terminal device 1to perform the channel compensation of the downlink physical channel.The downlink reference signal is used in order for the terminal device 1to calculate the downlink channel state information.

According to the present embodiment, the following five types ofdownlink reference signals are used.

-   -   Cell-specific Reference Signal (CRS)    -   UE-specific Reference Signal (URS) associated with the PDSCH    -   Demodulation Reference Signal (DMRS) associated with the EPDCCH    -   Non-Zero Power Chanel State Information-Reference Signal (NZP        CSI-RS)    -   Zero Power Chanel State Information-Reference Signal (ZP CSI-RS)    -   Multimedia Broadcast and Multicast Service over Single Frequency        Network Reference signal (MBSFN RS)    -   Positioning Reference Signal (PRS)

The CRS is transmitted in the entire band of a subframe. The CRS is usedto perform demodulation of the PBCH/PDCCH/PHICH/PCFICH/PDSCH. The CRSmay be used in order for the terminal device 1 to calculate the downlinkchannel state information. The PBCH/PDCCH/PHICH/PCFICH is transmitted onan antenna port used for transmission of the CRS.

The URS relating to the PDSCH is transmitted in a subframe and in a bandthat are used for transmission of the PDSCH to which the URS relates.The URS is used to demodulate the PDSCH to which the URS relates.

The PDSCH is transmitted on an antenna port used for transmission of theCRS or the URS. For example, a DCI format 1A is used to schedule thePDSCH transmitted on the antenna port used for the transmission of theCRS. For example, a DCI format 2B, a DCI format 2C, and a DCI format 2Dare used to schedule the PDSCH transmitted on the antenna port used forthe transmission of the URS.

The DMRS relating to the EPDCCH is transmitted in a subframe and in aband that are used for transmission of the EPDCCH to which the DMRSrelates. The DMRS is used to demodulate the EPDCCH to which the DMRSrelates. The EPDCCH is transmitted on an antenna port used fortransmission of the DMRS.

The NZP CSI-RS is transmitted in a subframe that is configured. Aresource in which the NZP CSI-RS is transmitted is configured by thebase station device. The NZP CSI-RS is used in order for the terminaldevice 1 to calculate the downlink channel state information. Theterminal device 1 uses the NZP CSI-RS to perform signal measurement(channel measurement). The NZP CSI-RS is transmitted on some or all ofthe transmit antenna ports 15 to 22. The terminal device 1configures/specifies the transmit antenna port for the NZP CSI-RStransmission based on information received from the base station device3.

A resource for the ZP CSI-RS is configured by the base station device 3.With zero output, the base station device 3 transmits the ZP CSI-RS. Tobe more precise, the base station device 3 does not transmit the ZPCSI-RS. The base station device 3 transmits neither the PDSCH nor theEPDCCH in a resource configured for the ZP CSI-RS. For example, in acertain cell, the terminal device 1 can measure interference in aresource to which the NZP CSI-RS corresponds.

The MBSFN RS is transmitted in the entire band of a subframe used fortransmission of the PMCH. The MBSFN RS is used to demodulate the PMCH.The PMCH is transmitted on the antenna port used for transmission of theMBSFN RS.

The PRS may be used for the measurement of a reference signal timedifference (RSTD). The RSTD is defined by a relative timing differencebetween a neighbor cell and a reference cell.

The downlink physical channels and the downlink physical signals arecollectively referred to as a downlink signal. The uplink physicalchannels and the uplink physical signals are collectively referred to asan uplink signal. The downlink physical channels and the uplink physicalchannels are collectively referred to as a physical channel. Thedownlink physical signals and the uplink physical signals arecollectively referred to as a physical signal.

The BCH, the MCH, the UL-SCH, and the DL-SCH are transport channels. Achannel used in the Medium Access Control (MAC) layer is referred to asa transport channel. The unit of the transport channel used in the MAClayer is referred to as a transport block (TB) or a MAC Protocol DataUnit (PDU). In the MAC layer, control of Hybrid Automatic Repeat reQuest(HARQ) is performed for each transport block. The transport block is aunit of data that the MAC layer delivers to the physical layer. In thephysical layer, the transport block is mapped to a code word, and codingprocessing is performed on a code word-by-code word basis.

A configuration of the radio frame according to the present embodimentwill be described below.

FIG. 2 is a diagram illustrating a schematic configuration of the radioframe according to the present embodiment. Each of the radio frames is10 ms in length. In FIG. 2, the horizontal axis is a time axis.Furthermore, each of the radio frames is constituted of two half frames.Each of the half frames is 5 ms in length. Each of the half frames isconstituted of five subframes. Each of the subframes is 1 ms in lengthand is defined by two consecutive slots. Each of the slots is 0.5 ms inlength. The i-th subframe within a radio frame is constituted of the(2×i)-th slot and the (2×i+1)-th slot. To be more precise, 10 subframescan be utilized at each interval of 10 ms.

According to the present embodiment, the following three types ofsubframes are defined.

-   -   Downlink subframe (a first subframe)    -   Uplink subframe (a second subframe)    -   Special subframe (a third subframe)

The downlink subframe is a subframe reserved for the downlinktransmission. The uplink subframe is a subframe reserved for the uplinktransmission. The special subframe is constituted of three fields. Thethree fields are a downlink pilot time slot (DwPTS), a guard period(GP), and an uplink pilot time slot (UpPTS). The sum of lengths of theDwPTS, the GP, and the UpPTS is 1 ms. The DwPTS is a field reserved forthe downlink transmission. The UpPTS is a field reserved for the uplinktransmission. The GP is a field in which neither the downlinktransmission nor the uplink transmission is performed. Moreover, thespecial subframe may be constituted of only the DwPTS and the GP, or maybe constituted of only the GP and the UpPTS.

A single radio frame is constituted of at least the downlink subframe,the uplink subframe, and the special subframe.

The radio communication system according to the present embodimentsupports 5 ms downlink-to-uplink switch-point periodicity and 10 msdownlink-to-uplink switch-point periodicity. In a case where thedownlink-to-uplink switch-point periodicity is 5 ms, both of the halfframes within the radio frame include the special subframe. In anothercase where the downlink-to-uplink switch-point periodicity is 10 ms,only the first half frame within the radio frame includes the specialsubframe.

A configuration of a slot of the present embodiment will be describedbelow.

FIG. 3 is a diagram illustrating a configuration of a slot according tothe present embodiment. According to the present embodiment, a normalCyclic Prefix (CP) is applied to an OFDM symbol. Moreover, an extendedCyclic Prefix (CP) may be applied to the OFDM symbol. The physicalsignal or the physical channel transmitted in each of the slots isexpressed by a resource grid. In FIG. 3, the horizontal axis is a timeaxis, and the vertical axis is a frequency axis. In downlink, theresource grid is defined by a plurality of subcarriers and a pluralityof OFDM symbols. In uplink, the resource grid is defined by a pluralityof subcarriers and a plurality of SC-FDMA symbols. The number ofsubcarriers constituting one slot depends on a cell bandwidth. Thenumber of OFDM symbols or SC-FDMA symbols constituting one slot isseven. Each element within the resource grid is referred to as aresource element. The resource element is identified by using asubcarrier number, and an OFDM symbol or SC-FDMA symbol number.

A resource block is used to express mapping of a certain physicalchannel (the PDSCH, the PUSCH, or the like) to resource elements. Forthe resource block, a virtual resource block and a physical resourceblock are defined. A certain physical channel is first mapped to thevirtual resource block. Thereafter, the virtual resource block is mappedto the physical resource block. One physical resource block is definedby seven consecutive OFDM symbols or SC-FDMA symbols in a time domainand by 12 consecutive subcarriers in a frequency domain. Therefore, onephysical resource block is constituted of (7×12) resource elements.Furthermore, one physical resource block corresponds to one slot in thetime domain and corresponds to 180 kHz in the frequency domain. Physicalresource blocks are numbered from 0 in the frequency domain.

FIG. 4 is a schematic block diagram illustrating a configuration of theterminal device 1 of the present embodiment. As is illustrated, theterminal device 1 is configured to include a higher layer processingunit 101, a control unit 103, a reception unit 105, a transmission unit107, and a transmit and receive antenna 109. Furthermore, the higherlayer processing unit 101 is configured to include a radio resourcecontrol unit 1011, a scheduling information interpretation unit 1013,and a channel state information (CSI) report control unit 1015.Furthermore, the reception unit 105 is configured to include a decodingunit 1051, a demodulation unit 1053, a demultiplexing unit 1055, a radioreception unit 1057, and a measurement unit 1059. The transmission unit107 is configured to include a coding unit 1071, a modulation unit 1073,a multiplexing unit 1075, a radio transmission unit 1077, and an uplinkreference signal generation unit 1079.

The higher layer processing unit 101 outputs the uplink data (thetransport block) generated by a user operation or the like, to thetransmission unit 107. The higher layer processing unit 101 performsprocessing of the Medium Access Control (MAC) layer, a Packet DataConvergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, anda Radio Resource Control (RRC) layer.

The radio resource control unit 1011 included in the higher layerprocessing unit 101 manages various pieces of configuration informationof the terminal device 1 itself. Furthermore, the radio resource controlunit 1011 generates information to be mapped to each uplink channel, andoutputs the generated information to the transmission unit 107.

The scheduling information interpretation unit 1013 included in thehigher layer processing unit 101 interprets the DCI format (schedulinginformation) received through the reception unit 105, generates controlinformation for control of the reception unit 105 and the transmissionunit 107, in accordance with a result of interpreting the DCI format,and outputs the generated control information to the control unit 103.

The CSI report control unit 1015 instructs the measurement unit 1059 toderive channel state information (RI/PMI/CQI) relating to the CSIreference resource. The CSI report control unit 1015 instructs thetransmission unit 107 to transmit the RI/PMI/CQI. The CSI report controlunit 1015 sets a configuration that is used when the measurement unit1059 calculates the CQI.

The control unit 103 generates a control signal for control of thereception unit 105 and the transmission unit 107, based on the controlinformation originating from the higher layer processing unit 101. Thecontrol unit 103 outputs the generated control signal to the receptionunit 105 and the transmission unit 107 to control the reception unit 105and the transmission unit 107.

In accordance with the control signal input from the control unit 103,the reception unit 105 demultiplexes, demodulates, and decodes areception signal received from the base station device 3 through thetransmit and receive antenna 109, and outputs the resulting informationto the higher layer processing unit 101.

The radio reception unit 1057 converts (down-converts) a downlink signalreceived through the transmit and receive antenna 109 into a signal ofan intermediate frequency, removes unnecessary frequency components,controls an amplification level in such a manner as to suitably maintaina signal level, performs orthogonal demodulation, based on an in-phasecomponent and an orthogonal component of the received signal, andconverts the resulting orthogonally-demodulated analog signal into adigital signal. The radio reception unit 1057 removes a portioncorresponding to a Guard Interval (GI) from the digital signal resultingfrom the conversion, performs Fast Fourier Transform (FFT) on the signalfrom which the guard interval has been removed, and extracts a signal inthe frequency domain.

The demultiplexing unit 1055 demultiplexes the extracted signal into thePHICH, the PDCCH, the EPDCCH, the PDSCH, and the downlink referencesignal. Furthermore, the demultiplexing unit 1055 makes a compensationof channels including the PHICH, the PDCCH, the EPDCCH, and the PDSCH,from a channel estimate input from the measurement unit 1059.Furthermore, the demultiplexing unit 1055 outputs the downlink referencesignal resulting from the demultiplexing, to the measurement unit 1059.

The demodulation unit 1053 multiplies the PHICH by a corresponding codefor composition, demodulates the resulting composite signal incompliance with a Binary Phase Shift Keying (BPSK) modulation scheme,and outputs a result of the demodulation to the decoding unit 1051. Thedecoding unit 1051 decodes the PHICH destined for the terminal device 1itself and outputs the HARQ indicator resulting from the decoding to thehigher layer processing unit 101. The demodulation unit 1053 demodulatesthe PDCCH and/or the EPDCCH in compliance with a QPSK modulation schemeand outputs a result of the demodulation to the decoding unit 1051. Thedecoding unit 1051 attempts to decode the PDCCH and/or the EPDCCH. In acase of succeeding in the decoding, the decoding unit 1051 outputsdownlink control information resulting from the decoding and an RNTI towhich the downlink control information corresponds, to the higher layerprocessing unit 101.

The demodulation unit 1053 demodulates the PDSCH in compliance with amodulation scheme notified with the downlink grant, such as QuadraturePhase Shift Keying (QPSK), 16 Quadrature Amplitude Modulation (QAM), or64 QAM, and outputs a result of the demodulation to the decoding unit1051. The decoding unit 1051 decodes the data based on information on acoding rate notified with the downlink control information, and outputs,to the higher layer processing unit 101, the downlink data (thetransport block) resulting from the decoding.

The measurement unit 1059 performs measurement of a downlink pathloss, achannel measurement, and/or an interference measurement from thedownlink reference signal input from the demultiplexing unit 1055. Themeasurement unit 1059 outputs the channel state information calculatedbased on the measurement result and the measurement result to the higherlayer processing unit 101. Furthermore, the measurement unit 1059calculates a downlink channel estimate from the downlink referencesignal and outputs the calculated downlink channel estimate to thedemultiplexing unit 1055.

The transmission unit 107 generates the uplink reference signal inaccordance with the control signal input from the control unit 103,codes and modulates the uplink data (the transport block) input from thehigher layer processing unit 101, multiplexes the PUCCH, the PUSCH, andthe generated uplink reference signal, and transmits a result of themultiplexing to the base station device 3 through the transmit andreceive antenna 109.

The coding unit 1071 codes the uplink control information and the uplinkdata input from the higher layer processing unit 101. The modulationunit 1073 modulates the coding bits input from the coding unit 1071, incompliance with the modulation scheme such as BPSK, QPSK, 16 QAM, or 64QAM.

The uplink reference signal generation unit 1079 generates a sequenceacquired according to a rule (formula) prescribed in advance, based on aphysical cell identifier (also referred to as a physical cell identity(PCI), a CELL ID, or the like) for identifying the base station device3, a bandwidth to which the uplink reference signal is mapped, a cyclicshift notified with the uplink grant, a parameter value for generationof a DMRS sequence, and the like.

Based on the information used for the scheduling of the PUSCH, themultiplexing unit 1075 determines the number of data sequences to bespatial-multiplexed, maps a plurality of pieces of uplink data to betransmitted on the same PUSCH to a plurality of sequences throughmultiple input multiple output spatial multiplexing (MIMO SM), andperforms precoding on the sequences.

In accordance with the control signal input from the control unit 103,the multiplexing unit 1075 performs Discrete Fourier Transform (DFT) onthe modulation symbols of the PUSCH. Furthermore, the multiplexing unit1075 multiplexes PUCCH and PUSCH signals and the generated uplinkreference signal for each transmit antenna port. To be more specific,the multiplexing unit 1075 maps the PUCCH and PUSCH signals and thegenerated uplink reference signal to the resource elements for eachtransmit antenna port.

The radio transmission unit 1077 performs Inverse Fast Fourier Transform(IFFT) on a signal resulting from the multiplexing, performs modulationin compliance with an SC-FDMA scheme, attaches the guard interval to theSC-FDMA-modulated SC-FDMA symbol, generates a baseband digital signal,converts the baseband digital signal into an analog signal, generates anin-phase component and an orthogonal component of an intermediatefrequency from the analog signal, removes frequency componentsunnecessary for the intermediate frequency band, converts (up-converts)the signal of the intermediate frequency into a signal of a highfrequency, removes unnecessary frequency components, performs poweramplification, and outputs a final result to the transmit and receiveantenna 109 for transmission.

FIG. 5 is a schematic block diagram illustrating a configuration of thebase station device 3 according to the present embodiment. As isillustrated, the base station device 3 is configured to include a higherlayer processing unit 301, a control unit 303, a reception unit 305, atransmission unit 307, and a transmit and receive antenna 309. Thehigher layer processing unit 301 is configured to include a radioresource control unit 3011, a scheduling unit 3013, and a CSI reportcontrol unit 3015. The reception unit 105 is configured to include adecoding unit 3051, a demodulation unit 3053, a demultiplexing unit3055, a radio reception unit 3057, and a measurement unit 3059. Thetransmission unit 307 is configured to include a coding unit 3071, amodulation unit 3073, a multiplexing unit 3075, a radio transmissionunit 3077, and a downlink reference signal generation unit 3079.

The higher layer processing unit 301 performs processing of the MediumAccess Control (MAC) layer, the Packet Data Convergence Protocol (PDCP)layer, the Radio Link Control (RLC) layer, and the Radio ResourceControl (RRC) layer. Furthermore, the higher layer processing unit 301generates control information for control of the reception unit 305 andthe transmission unit 307, and outputs the generated control informationto the control unit 303.

The radio resource control unit 3011 included in the higher layerprocessing unit 301 generates, or acquires from a higher node, thedownlink data (the transport block) arranged in the downlink PDSCH,system information, the RRC message, the MAC control element (CE), andthe like, and outputs a result of the generation or the acquirement tothe transmission unit 307. Furthermore, the radio resource control unit3011 manages various configuration information for each of the terminaldevices 1.

The scheduling unit 3013 included in the higher layer processing unit301 determines a frequency and a subframe to which the physical channels(the PDSCH and the PUSCH) are allocated, the coding rate and modulationscheme for the physical channels (the PDSCH and the PUSCH), the transmitpower, and the like, from the received channel state information andfrom the channel estimate, channel quality, or the like input from thechannel measurement unit 3059. The scheduling unit 3013 generates thecontrol information in order to control the reception unit 305 and thetransmission unit 307 in accordance with a result of the scheduling, andoutputs the generated information to the control unit 303. Thescheduling unit 3013 generates the information (for example, a DCIformat) to be used for the scheduling of the physical channels (thePDSCH and the PUSCH), based on the result of the scheduling.

The CSI report control unit 3015 included in the higher layer processingunit 301 controls a CSI report that is made by the terminal device 1.The CSI report control unit 3015 transmits information that is assumedin order for the terminal device 1 to derive a RI/PMI/CQI in the CSIreference resource and that shows various configurations, to theterminal device 1 through the transmission unit 307.

The control unit 303 generates a control signal for controlling thereception unit 305 and the transmission unit 307, based on the controlinformation originating from the higher layer processing unit 301. Thecontrol unit 303 outputs the generated control signal to the receptionunit 305 and the transmission unit 307 to control the reception unit 305and the transmission unit 307.

In accordance with the control signal input from the control unit 303,the reception unit 305 demultiplexes, demodulates, and decodes thereception signal received from the terminal device 1 through thetransmit and receive antenna 309, and outputs information resulting fromthe decoding to the higher layer processing unit 301. The radioreception unit 3057 converts (down-converts) an uplink signal receivedthrough the transmit and receive antenna 309 into a signal of anintermediate frequency, removes unnecessary frequency components,controls the amplification level in such a manner as to suitablymaintain a signal level, performs orthogonal demodulation based on anin-phase component and an orthogonal component of the received signal,and converts the resulting orthogonally-demodulated analog signal into adigital signal.

The radio reception unit 3057 removes a portion corresponding to theGuard Interval (GI) from the digital signal resulting from theconversion. The radio reception unit 3057 performs Fast FourierTransform (FFT) on the signal from which the guard interval has beenremoved, extracts a signal in the frequency domain, and outputs theresulting signal to the demultiplexing unit 3055.

The demultiplexing unit 1055 demultiplexes the signal input from theradio reception unit 3057 into the PUCCH, the PUSCH, and the signal suchas the uplink reference signal. Note that the demultiplexing isperformed, based on radio resource allocation information that isdetermined in advance by the base station device 3 using the radioresource control unit 3011 and that is included in the uplink grantnotified to each of the terminal devices 1. Furthermore, thedemultiplexing unit 3055 makes a compensation of channels including thePUCCH and the PUSCH from the channel estimate input from the measurementunit 3059. Furthermore, the demultiplexing unit 3055 outputs an uplinkreference signal resulting from the demultiplexing, to the measurementunit 3059.

The demodulation unit 3053 performs Inverse Discrete Fourier Transform(IDFT) on the PUSCH, acquires modulation symbols, and performs receptionsignal demodulation, that is, demodulates each of the modulation symbolson the PUCCH and the PUSCH, in compliance with the modulation schemeprescribed in advance, such as Binary Phase Shift Keying (BPSK), QPSK,16 QAM, or 64 QAM, or in compliance with the modulation scheme that thebase station device 3 itself notifies in advance each of the terminaldevices 1 with the uplink grant. The demodulation unit 3053demultiplexes the modulation symbols of a plurality pieces of uplinkdata transmitted on the identical PUSCH with the MIMO SM, based on thenumber of spatial-multiplexed sequences notified in advance with theuplink grant to each of the terminal devices 1 and informationindicating the precoding to be performed on the sequences.

The decoding unit 3051 decodes the coding bits of the PUCCH and thePUSCH, which have been demodulated, at the coding rate in compliancewith a coding scheme prescribed in advance, the coding rate beingprescribed in advance or being notified in advance with the uplink grantto the terminal device 1 by the base station device 3 itself, andoutputs the decoded uplink data and uplink control information to thehigher layer processing unit 101. In a case that the PUSCH isre-transmitted, the decoding unit 3051 performs the decoding with thecoding bits input from the higher layer processing unit 301 and retainedin an HARQ buffer, and the demodulated coding bits. The measurement unit309 measures the channel estimate, the channel quality, and the like,based on the uplink reference signal input from the demultiplexing unit3055, and outputs a result of the measurement to the demultiplexing unit3055 and the higher layer processing unit 301.

The transmission unit 307 generates the downlink reference signal inaccordance with the control signal input from the control unit 303,codes and modulates the HARQ indicator, the downlink controlinformation, and the downlink data that are input from the higher layerprocessing unit 301, multiplexes the PHICH, the PDCCH, the EPDCCH, thePDSCH, and the downlink reference signal, and transmits a result of themultiplexing to the terminal device 1 through the transmit and receiveantenna 309.

The coding unit 3071 codes the HARQ indicator, the downlink controlinformation, and the downlink data input from the higher layerprocessing unit 301. The modulation unit 3073 modulates the coding bitsinput from the coding unit 3071, in compliance with the modulationscheme, such as BPSK, QPSK, 16 QAM, or 64 QAM.

The downlink reference signal generation unit 3079 generates, as thedownlink reference signal, a sequence that is already known to theterminal device 1 and that is acquired in accordance with a ruleprescribed in advance, based on the physical cell identifier (PCI) foridentifying the base station device 3, and the like.

In accordance with the number of PDSCH layers to be spatial-multiplexed,the multiplexing unit 3075 maps one or more downlink data transmitted onone PUSCH to one or more layers, and performs a precoding for the one ormore layers. The multiplexing unit 375 multiplexes a signal of thedownlink physical channel and the downlink reference signal for eachtransmit antenna port. The multiplexing unit 375 arranges the signal ofthe downlink physical channel and the downlink reference signal to theresource element for each transmit antenna port.

The radio transmission unit 3077 performs Inverse Fast Fourier Transform(IFFT) on the modulation symbol resulting from the multiplexing or thelike, performs the modulation in compliance with an OFDM scheme togenerate an OFDM symbol, attaches the guard interval to theOFDM-modulated OFDM symbol, generates a digital signal in a baseband,converts the digital signal in the baseband into an analog signal,generates an in-phase component and an orthogonal component of anintermediate frequency from the analog signal, removes frequencycomponents unnecessary for the intermediate frequency band, converts(up-converts) the signal of the intermediate frequency into a signal ofa high frequency signal, removes unnecessary frequency components,performs power amplification, and outputs a final result to the transmitand receive antenna 309 for transmission.

FIG. 6 is a diagram illustrating one example of processing in the codingunit 3071 according to the present embodiment. The coding unit 3071 mayapply the processing of FIG. 6 to each of transport blocks. Onetransport block is mapped to one code word. That is, coding of atransport block is identical to coding of a code word.

After attaching corresponding CRC parity bits to one code word inputfrom the higher layer processing unit 301, the coding unit 3071 dividesthe code word into one or more code blocks (S600). The corresponding CRCparity bits may be attached to each of the code blocks.

Each of the one or more code blocks is coded (for example, turbo-codedor convolutional-coded) (S601). A rate matching is applied to each of asequence of coding bits of the code blocks (S602). A sequence of codingbits of a code word is obtained by connecting the one or more codeblocks to which the rate matching is applied (S603). The sequence of thecoding bits of the code word is output to the modulation unit 3073.

FIG. 7 is a diagram illustrating one example of processing in themultiplexing unit 3075 according to the present embodiment. Themultiplexing unit 3075 maps a complex valued symbol of a first code wordand a complex valued symbol of a second code word input from themodulation unit 3073 to one or more layers (S700). Note that only thecomplex valued symbol of the first code word may be input from themodulation unit 3073. Note that the number of code words to be input isequal to or less than the number of layers.

Precoding is applied to the complex valued symbol mapped to the layers(S701). The sequences of the complex valued symbols equal in number tothe number of corresponding transmit antenna ports are generated by theprecoding. Note that the number of the layers is equal to or less thanthe number of the transmit antenna ports corresponding to thetransmission of the PDSCH. The complex valued symbol to which theprecoding is applied is mapped to a resource element for each transmitantenna port corresponding to the transmission of the PDSCH (S702).

The terminal device 1 configures a transmission mode for the PDSCHtransmission, based on information received from the base station device3. The terminal device 1 is configured, by a higher layer, to receivethe PDSCH data transmission signaled through the PDCCH, in accordancewith the transmission mode. The terminal device 1 selects a DCI formatto be monitored, in accordance with the transmission mode. Furthermore,the terminal device 1 specifies, in accordance with the transmissionmode and the received DCI format, the transmission scheme of the PDSCHcorresponding to the DCI format.

FIG. 8 is a table showing one example of a correspondence of atransmission mode, a DCI format, and a PDSCH transmission schemeaccording to the present embodiment. A column P800 in FIG. 8 indicates atransmission mode. A column P801 in FIG. 8 indicates a DCI format. Acolumn P802 in FIG. 8 indicates a transmission scheme of the PDSCHcorresponding to the PDCCH and the number of layers supported by thetransmission scheme of the PDSCH. For example, in FIG. 8, in a case ofthe terminal device 1 being configured with a transmission mode 4, andreceiving a DCI format 2 on a PDCCH, the transmission scheme of thePDSCH corresponding to the PDCCH is closed-loop spatial multiplexing (upto four layers) or transmit diversity (one layer). Note that informationincluded in the DCI format 2 indicates either one of the closed-loopspatial multiplexing or the transmission diversity. Furthermore, theinformation included in the DCI format 2 indicates the number of layersto be spatial-multiplexed.

The terminal device 1 transmits, to the base station device 3,capability information (UECapabilityInformation). The base stationdevice 3 configures the terminal device 1 and performs scheduling forthe terminal device 1, based on the capability information.

The capability information may include a plurality of capabilityparameters (UE radio access capability parameters). One capabilityparameter corresponds to one function or one group of functions. Onecapability parameter may indicate whether the corresponding function orthe corresponding group of functions were tested successfully. Onecapability parameter may indicate whether the terminal device 1 supportsthe corresponding function or the corresponding group of functions. Thecapability information is RRC layer information. The capabilityparameter is an RRC layer parameter.

The capability information may include one or more capability parametersindicating a UE category. The capability information may include onecapability parameter indicating a downlink UE category. In the presentembodiment, the downlink UE category is defined separately from the UEcategory. The UE category and the downlink UE category correspond to thetotal number of DL-SCH soft channel bits and the maximum number ofsupported layers for spatial multiplexing in the downlink. The totalnumber of DL-SCH soft channel bits is a total number of soft channelbits capable of being utilized for HARQ processing of the DL-SCH.

FIG. 9 is a table showing one example of a UE category according to thepresent embodiment. A column P900 of FIG. 9 indicates the capabilityparameter indicating the UE category. A column P901 of FIG. 9 indicatesthe UE category indicated by the capability parameter. P902 of FIG. 9indicates a total number of DL-SCH soft channel bits to which the UEcategory corresponds. P903 of FIG. 9 indicates the maximum number ofsupported layers for the spatial multiplexing in the downlink to whichthe UE category corresponds. The capability parameter ue-Category(without suffix) indicates any one of UE categories 1 to 5. A capabilityparameter ue-Category-v1020 indicates any one of UE categories 6 to 8. Acapability parameter ue-Category-v1170 indicates any one of UEcategories 9 and 10. A capability parameter ue-Category-v11a0 indicatesany one of UE categories 11 and 12.

FIG. 10 is a table showing one example of a downlink UE categoryaccording to the present embodiment. A column P1000 of FIG. 10 indicatesa capability parameter indicating the downlink UE category. A columnP1001 of FIG. 10 indicates the downlink UE category indicated by thecapability parameter. P1002 of FIG. 10 indicates the total number ofDL-SCH soft channel bits to which the downlink UE category corresponds.P1003 of FIG. 10 indicates the maximum number of supported layers forthe spatial multiplexing in the downlink to which the downlink UEcategory corresponds. A capability parameter ue-Category DL-r12indicates any one of downlink UE categories 0, 6, 7, 9, 10, 11, 12, 13,and 14.

FIG. 11 is a table showing one example of a combination of categoriesindicated by a plurality of capability parameters according to thepresent embodiment. A case 9 of FIG. 11 expresses, in a case that thecapability parameter ue-CategoryDL-r12 indicates a downlink UE category9, that the capability parameter ue-Category-v1020 indicates the UEcategory 6 and the capability parameter ue-Category (without suffix)indicates the UE category 4.

The capability information may include the capability parametersupportedBandCombination indicating carrier aggregation and MIMOsupported by the terminal device 1. The capability parametersupportedBandCombination indicates one or more band combinations. Theone band combination includes one or more bands. The one band includesone or more combinations of a bandwidth class to be supported and MIMOcapabilities for the downlink. That is, the terminal device 1 provides,to the base station device 3, for each bandwidth class of each band ofeach band combination specified in the capability parametersupportedBandCombination, the MIMO capability for the downlink. The MIMOcapability for the downlink indicates the maximum number of layerssupported by the terminal device 1, and applies to all componentcarriers (cells) corresponding to the bandwidth class.

The bandwidth class corresponds to an aggregated transmission bandwidthconfiguration and the maximum number of component carrier which aresupported by the terminal device 1 for the bandwidth class. Theaggregated transmission bandwidth configuration is defined by the totalnumber of resource blocks included in the component carrier aggregatedin the corresponding bands. Note that the plurality of componentcarriers corresponding to the bandwidth class are contiguous in thefrequency region. There may be a guard band of 300 kHz or smallerbetween the component carriers contiguous in the frequency region.

FIG. 12 is a table showing one example of the bandwidth class accordingto the present embodiment. In FIG. 12, in a case that the bandwidthclass is C, the aggregated transmission bandwidth configuration may begreater than 25, equal to or less than 100, and the maximum number ofthe component carriers is 2.

FIG. 13 and FIG. 14 are diagrams illustrating one example of aconfiguration of the capability parameter supportedBandCombinationaccording to the present embodiment. The capability parametersupportedBandCombination is included in a capability parameterRF-Parameters-r10. The capability parameter supportedBandCombinationincludes one or more parameters, BandCombinationParameters-r10. Thecapability parameter supportedBandCombination indicates a bandcombination. The parameter BandCombinationParameters-r10 includes one ormore parameters, BandParameters-r100. The parameter BandParameters-r100indicates one band.

A parameter FreqBandIndicator included in the parameterBandParameters-r100 indicates a frequency of a corresponding band. Aparameter bandParametersUL-r10 included in the parameterBandParameters-r100 includes one or more parametersCA-MIMO-ParametersUL-r10. The parameter CA-MIMO-ParametersUL-r10includes a parameter ca-BandwidthClassUL-r10 and a parametersupportedMIMO-CapabilityUL-r10. The parameter ca-BandwidthClassUL-r10indicates a bandwidth class for the uplink in the corresponding band.The parameter supportedMIMO-CapabilityUL-r100 indicates the MIMOcapability (the maximum number of layers supported by the terminaldevice 1) for the uplink in the corresponding band. That is, theparameter ca-BandwidthClassUL-r10 indicates one combination of thebandwidth class and the MIMO capability for the uplink.

A parameter bandParametersDL-r10 included in the parameterBandParameters-r10 includes one or more parametersCA-MIMO-ParametersDL-r10. The parameter CA-MIMO-ParametersDL-r10includes a parameter ca-BandwidthClassDL-r10 and a parametersupportedMIMO-CapabilityDL-r10. The parameter ca-BandwidthClassDL-r10indicates the bandwidth class for the downlink in the correspondingband. The parameter supportedMIMO-CapabilityDL-r10 indicates the MIMOcapability (the maximum number of layers supported by the terminaldevice 1) for the downlink in the corresponding band. That is, theparameter ca-BandwidthClassDL-r10 indicates one combination of thebandwidth class and the MIMO capability for the downlink.

The capability parameter supportedBandCombination may indicate the MIMOcapability (the maximum number of layers supported by terminal device 1)not involving carrier aggregation.

For each bandwidth class of each band of each band combination specifiedin the capability parameter supportedBandCombination, the terminaldevice 1 further indicates the maximum number of layers supported by theterminal device 1, and provides, to the base station device, the MIMOcapability (parameter supportedMIMO-CapabilityDL-v10xx) applied to anyone of the downlink component carriers corresponding to the bandwidthclass. The parameter supportedMIMO-CapabilityDL-v10xx may be included inthe capability information, for each bandwidth class of each band ofeach band combination specified in the capability parametersupportedBandCombination.

That is, for each of the bandwidth class (parameterca-BandwidthClassDL-r10) of each band of each band combination specifiedin the capability parameter supportedBandCombination, the terminaldevice 1 provides, to the base station device 3, the MIMO capability(parameter supportedMIMO-CapabilityDL-r100) for the downlink applied toall downlink component carriers corresponding to the bandwidth class,and the MIMO capability (parameter supportedMIMO-CapabilityDL-v100xx)applied to each of the downlink component carriers corresponding to thebandwidth class. Note that the parametersupportedMIMO-CapabilityDL-v100xx may not be included in the capabilityparameter supportedBandCombination.

FIG. 15 is a table showing one example of a combination of a bandwidthclass and the MIMO capability according to the present embodiment. Theterminal device 1 may provide four combinations indicated in FIG. 15 tothe base station device 3, for one band in one combination of bandsspecified in the capability parameter supportedBandCombination. In FIG.15, in a case that the bandwidth class is B, the parametersupportedMIMO-CapabilityDL-r10 indicates 2, and the parametersupportedMIMO-CapabilityDL-v10xx indicates {4,2}.

In FIG. 15, the base station device 3 that cannot decode the parametersupportedMIMO-CapabilityDL-v10xx determines that the maximum number oflayers supported in each of two downlink component carriers (two cells)configured in the corresponding band is 2.

In FIG. 15, the base station device 3 that can decode the parametersupportedMIMO-CapabilityDL-v10xx determines that the maximum number oflayers supported in one of the two downlink component carriers (twocells) configured in the corresponding band is 4, and the maximum numberof layers supported in the other of the two downlink component carriersis 2.

Hereinafter, in the description of FIG. 15, it is assumed that twodownlink component carriers are configured in one band for the terminaldevice 1. Here, a downlink component carriers out of the two downlinkcomponent carriers to which the PDSCH (DL-SCH) transmission involving upto four layers is applied may be controlled by the base station device3. The base station device 3 may transmit, to the terminal device 1, aparameter LayersCount-v100xx applied to only a first downlink componentcarrier being one of the two downlink component carriers and indicatingthe maximum number of layers. The base station device 3 may transmit, tothe terminal device 1, a parameter LayersCount-v100xx applied to only asecond downlink component carrier being one of the two downlinkcomponent carriers and indicating the maximum number of layers. Theparameter LayersCount-v100xx is a parameter of the RRC layer.

For example, in FIG. 15, the base station device 3 may transmit, to theterminal device 1, a parameter LayersCount-v10xx that is the parameterLayersCount-v100xx for the first downlink component carrier being one ofthe two downlink component carriers and indicates 4, and a parameterLayersCount-v10xx that is the parameter LayersCount-v10xx for the seconddownlink component carrier being one of the two downlink componentcarriers and indicates 2.

For example, in FIG. 15, in a case that a parameter LayersCount-v10xxfor the first downlink component carrier being one of the two downlinkcomponent carriers is received/configured, the terminal device 1 maydetermine that up to four layers indicated by the parameterLayersCount-v10xx are applied to the PDSCH (DL-SCH) transmission in thefirst downlink component carrier being one of the two downlink componentcarriers.

For example, in FIG. 15, in a case that the parameter LayersCount-v10xxfor the second downlink component carrier being one of the two downlinkcomponent carriers is not received/configured, the terminal device 1 maydetermine that up to two layers indicated by the parametersupportedMIMO-CapabilityDL-r10 are applied to the PDSCH (DL-SCH)transmission in the second downlink component carrier being one of thetwo downlink component carriers.

For example, in FIG. 15, in a case that the parametersupportedMIMO-CapabilityDL-r10 and the parametersupportedMIMO-CapabilityDL-r100xx are not included in the capabilityinformation, the terminal device 1 may determine that up to the maximumnumber of layers to which the capability parameter ue-Category (withoutsuffix) corresponds are applied to the PDSCH (DL-SCH) transmission inthe first downlink component carrier being one of the two downlinkcomponent carriers.

FIG. 16 is diagram illustrating one example of a sequence chart betweenthe terminal device 1 and the base station device 3 according to thepresent embodiment.

The base station device 3 transmits a UECapabilityEnquiry message to theterminal device 1 (S160). The UECapabilityEnquiry message is a messageof the RRC layer. The UECapabilityEnquiry message is used to requesttransmission of the capability information (UECapabilitylnformation). Ina case of receiving the UECapabilityEnquiry message, the terminal device1 transmits the capability information (UECapabilitylnformation) to thebase station device 3 (S161).

The base station device 3 determines, in accordance with the receivedcapability information (UECapabilitylnformation), the configuration forcarrier aggregation, the transmission mode for the PDSCH transmission,and/or the MIMO for the PDSCH transmission, for the terminal device 1(S162). The base station device 3 transmits anRRCConnectionReconfiguration message to the terminal device 1 (S163).The RRCConnectionReconfiguration message transmits information on theRRC layer for the configuration determined in S161. TheRRCConnectionReconfiguration message is a command to correct an RRCconnection. The RRCConnectionReconfiguration message may include theparameter LayersCount-v10xx.

The terminal device 1 corrects/reconfigures the RRC connection, inaccordance with the received RRCConnectionReconfiguration message. Thatis, the terminal device 1 corrects/reconfigures carrier aggregation, thetransmission mode for the PDSCH transmission, and/or the MIMO for thePDSCH transmission, in accordance with the receivedRRCConnectionReconfiguration message. After correcting the RRCconnection in accordance with the received RRCConnectionReconfigurationmessage, the terminal device 1 transmits anRRCConnectionReconfigurationComplete message to the base station device3. The RRCConnectionReconfigurationComplete message is a message of theRRC layer. The RRCConnectionReconfigurationComplete message is used forconfirming a successful completion of the RRC connectionreconfiguration.

The terminal device 1 and the base station device 3 specify the bitwidth of an RI, based on the configuration determined in S162 and/or thecapability information (UECapabilityInformation) (S165). The terminaldevice 1 transmits the RI having the bit width determined in S165 on thePUCCH or the PUSCH to the base station device 3. The base station device3 performs processing of receiving (demultiplexing, demodulating, and/ordecoding) the RI, by assuming the RI having the bit width determined inS165.

The bit width of the RI is given for each corresponding downlinkcomponent carrier (cell). The bit width of the RI corresponding to adifferent downlink component carrier may be different from each other.In a case that the maximum number of layers of the downlink (PDSCH) inthe corresponding downlink component carrier is 2, the bit width of theRI is “1”. In a case that the maximum number of the layers of thedownlink (PDSCH) in the corresponding downlink component carrier is 4,the bit width of the RI is “2”. In a case that the maximum number of thelayers of the downlink (PDSCH) in the corresponding downlink componentcarrier is 8, the bit width of the RI is “3”.

The terminal device 1 and the base station device 3 specify the softbuffer size for the code block of the transport block (code word)transmitted on the PDSCH, and the rate matching for the code block,based on the configuration determined in S162 and/or the capabilityinformation (UECapabilityInformation) (S167).

The base station device 3 codes the transport block and transmits thecoded transport block to the terminal device 1 on the PDSCH, inaccordance with the rate matching for the code block of the transportblock specified in S167 (S168). The terminal device 1 performsprocessing of receiving (decoding) the transport block, in accordancewith the rate matching for the code block of the transport blockspecified in S167.

The terminal device 1 stores, in a case of failing to decode the codeblock of the transport block, some or all of the soft channel bits ofthe code block (S169). The soft channel bits of the code block to bestored is given by referring to the soft buffer size for the code blockof the transport block specified in S167. The stored soft channel bitsare utilized for HARQ processing for the code block. The stored softchannel bits may be combined with the re-transmitted soft channel bits.

Hereinafter, a first example associated with a method of specifying thebit width for the RI in step S165 of FIG. 16 will be described. Thefirst example is applied to the terminal device 1.

(1-1) In the first example, the terminal device 1 includes: atransmission unit 107 configured to transmit a Rank Indicator (RI)determined by a terminal device, the RI corresponding to PhysicalDownlink Shared CHannel (PDSCH) transmission in a first downlinkcomponent carrier corresponding to a first bandwidth class of a firstband in a first band combination and corresponding to the number ofuseful layers; and a reception unit 105 configured to receive the PDSCH.Here, the transmission unit 107 transmits capability information(UECapabilityInformation) including first information (ue-Category(without suffix)), second information (ca-BandwidthClassDL-r10), thirdinformation (supportedMIMO-CapabilityDL-r10), and/or fourth information(supportedMIMO-CapabilityDL-v10xx). Here, the reception unit 105receives fifth information (LayersCount-v10xx) for the first downlinkcomponent carrier corresponding to the first bandwidth class of thefirst band in the first band combination. Here, the first information(ue-Category (without suffix)) indicates a UE category corresponding toa first maximum number of the layers supported by the terminal device inthe downlink. Here, the second information (ca-BandwidthClassDL-r10)indicates the first bandwidth class that is for the first band in thefirst band combination and corresponds to the number of downlinkcomponent carriers supported by the terminal device. Here, the thirdinformation (supportedMIMO-CapabilityDL-r10) is applied to all of one ormore downlink component carriers corresponding to the first bandwidthclass of the first band in the first band combination, and indicates asecond maximum number of the layers supported by the terminal device inthe downlink. Here, the fourth information(supportedMIMO-CapabilityDL-v10xx) is applied to any one of the one ormore downlink component carriers corresponding to the first bandwidthclass of the first band in the first band combination, and indicates athird maximum number of the layers supported by the terminal device inthe downlink. Here, the fifth information (LayersCount-v10xx) indicatesa fourth maximum number of the layers. Here, a fifth maximum number ofthe layers assumed for determining a bit width for the RI is given,based on whether the fifth information for the first downlink componentcarrier corresponding to the first bandwidth class of the first band inthe first band combination is configured, by referring to any one of thefirst maximum number of the layers corresponding to the firstinformation, the second maximum number of the layers indicated by thethird information, and the fourth maximum number of the layers indicatedby the fifth information. Here, the bit width for the RI is given byreferring to the fifth maximum number of the layers.

(1-2) In the first example, in a case that the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured, the fifth maximum number ofthe layers assumed for determining the bit width for the RI is given byreferring to any one of the first maximum number of the layers and thesecond maximum number of the layers. Here, in a case that the fifthinformation (LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is configured, the fifth maximum number of thelayers assumed for determining the bit width for the RI is given byreferring to the fourth maximum number of the layers.

(1-3) In the first example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is configured; and a first transmission mode (forexample, a transmission mode 9) for the PDSCH transmission for the firstdownlink component carrier is configured, the fifth maximum number ofthe layers assumed for determining the bit width for the RI isdetermined in accordance with a smallest of (i) the number of configuredfirst ports and (ii) the third maximum number of the layers. Here, thefirst port is a transmit antenna port for a Chanel StateInformation-Reference Signal (CSI-RS).

(1-4) In the first example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is configured; and a second transmission mode(for example, a transmission mode 4) for the PDSCH transmission for thefirst downlink component carrier is configured, the fifth maximum numberof the layers assumed for determining the bit width for the RI isdetermined in accordance with a smallest of (i) the number of secondports and (ii) the third maximum number of the layers. Here, the secondport is a transmit antenna port for the Physical Broadcast CHannel(PBCH). That is, in the case that: the fifth information for the firstdownlink component carrier corresponding to the first bandwidth class ofthe first band in the first band combination is configured; and thesecond transmission mode for the PDSCH transmission is configured forthe first downlink component carrier, the fifth maximum number of thelayers assumed for determining the bit width for the RI is determined inaccordance with at least the third maximum number of the layersindicated by the fifth information.

(1-5) In the first example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured; the first transmission mode(for example, the transmission mode 9) for the PDSCH transmission forthe first downlink component carrier is configured; and the thirdinformation (supportedMIMO-CapabilityDL-r100) is included in thecapability information (UECapabilityInformation), the fifth maximumnumber of the layers assumed for determining the bit width for the RI isdetermined in accordance with a smallest of (i) the number of configuredfirst ports and (ii) the second maximum number of the layers indicatedby the third information. Here, the first port is a transmit antennaport for a Chanel State Information-Reference Signal (CSI-RS).

(1-6) In the first example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured; the first transmission mode(for example, the transmission mode 9) for the PDSCH transmission forthe first downlink component carrier is configured; and the thirdinformation (supportedMIMO-CapabilityDL-r100) is not included in thecapability information (UECapabilityInformation), the fifth maximumnumber of the layers assumed for determining the bit width for the RI isdetermined in accordance with a smallest of (i) the number of configuredfirst ports and (ii) the first maximum number of the layerscorresponding to the first information. Here, the first port is atransmit antenna port for a Chanel State Information-Reference Signal(CSI-RS).

(1-7) In the first example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured; and the second transmissionmode (for example, the transmission mode 4) for the PDSCH transmissionfor the first downlink component carrier is configured, the fifthmaximum number of the layers assumed for determining the bit width forthe RI is determined in accordance with a smallest of (i) the number ofsecond ports and (ii) the first maximum number of the layerscorresponding to the first information. Here, the second port is atransmit antenna port for the Physical Broadcast CHannel (PBCH).

(1-8) In the first example, the transmission unit 107 transmits the RIon a Physical Uplink Shared CHannel (PUSCH).

Hereinafter, a second example associated with the method of specifyingthe bit width for the RI in step S165 of FIG. 16 will be described. Thesecond example is applied to the base station device 3.

(2-1) In the second example, the base station device 3 includes: areception unit 305 configured to receive, from a terminal device, a RankIndicator (RI) determined by the terminal device, the RI correspondingto Physical Downlink Shared CHannel (PDSCH) transmission in a firstdownlink component carrier corresponding to a first bandwidth class of afirst band in a first band combination and corresponding to the numberof useful layers; and a transmission unit 307 configured to transmit thePDSCH to the terminal device. Here, the reception unit 305 receives,from the terminal device, capability information(UECapabilitylnformation) including first information (ue-Category(without suffix)), second information (ca-BandwidthClassDL-r10), thirdinformation (supportedMIMO-CapabilityDL-r10), and/or fourth information(supportedMIMO-CapabilityDL-v100xx). Here, the transmission unit 307transmits, to the terminal device, fifth information (LayersCount-v10xx)for the first downlink component carrier corresponding to the firstbandwidth class of the first band in the first band combination.

Here, the first information (ue-Category (without suffix)) indicates aUE category corresponding to a first maximum number of the layerssupported by the terminal device in the downlink. Here, the secondinformation (ca-BandwidthClassDL-r10) indicates the first bandwidthclass that is for the first band in the first band combination andcorresponds to the number of downlink component carriers supported bythe terminal device. Here, the third information(supportedMIMO-CapabilityDL-r10) is applied to all of one or moredownlink component carriers corresponding to the first bandwidth classof the first band in the first band combination, and indicates a secondmaximum number of the layers supported by the terminal device in thedownlink. Here, the fourth information(supportedMIMO-CapabilityDL-v10xx) is applied to any one of the one ormore downlink component carriers corresponding to the first bandwidthclass of the first band in the first band combination, and indicates athird maximum number of the layers supported by the terminal device inthe downlink. Here, the fifth information (LayersCount-v10xx) indicatesa fourth maximum number of the layers. A fifth maximum number of thelayers assumed for determining a bit width for the RI is given, based onwhether the fifth information (LayersCount-v10xx) for the first downlinkcomponent carrier corresponding to the first bandwidth class of thefirst band in the first band combination is configured for the terminaldevice, by referring to any one of the first maximum number of thelayers corresponding to the first information, the second maximum numberof the layers indicated by the third information, and the fourth maximumnumber of the layers indicated by the fifth information.

(2-2) In the second example, in a case that the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured for the terminal device, thefifth maximum number of the layers assumed for determining the bit widthfor the RI is given by referring to any one of the first maximum numberof the layers and the second maximum number of the layers. Here, in acase that the fifth information (LayersCount-v10xx) for the firstdownlink component carrier corresponding to the first bandwidth class ofthe first band in the first band combination is configured for theterminal device, the fifth maximum number of the layers assumed fordetermining the bit width for the RI is given by referring to the fourthmaximum number of the layers.

(2-3) In the second example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is configured for the terminal device; and afirst transmission mode (for example, a transmission mode 9) for thePDSCH transmission for the first downlink component carrier isconfigured for the terminal device, the fifth maximum number of thelayers assumed for determining the bit width for the RI is determined inaccordance with a smallest of (i) the number of configured first portsand (ii) the third maximum number of the layers, here, the first port isa transmit antenna port for a Chanel State Information-Reference Signal(CSI-RS).

(2-4) In the second example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is configured for the terminal device; and asecond transmission mode (for example, a transmission mode 4) for thePDSCH transmission for the first downlink component carrier isconfigured for the terminal device, the fifth maximum number of thelayers assumed for determining the bit width for the RI is determined inaccordance with a smallest of (i) the number of second ports and (ii)the third maximum number of the layers. Here, the second port is atransmit antenna port for the Physical Broadcast CHannel (PBCH). Thatis, in a case that: the fifth information for the first downlinkcomponent carrier corresponding to the first bandwidth class of thefirst band in the first band combination is configured; and the secondtransmission mode for the PDSCH transmission is configured for the firstdownlink component carrier, the fifth maximum number of the layersassumed for determining the bit width for the RI is determined inaccordance with at least the third maximum number of the layersindicated by the fifth information.

(2-5) In the second example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured for the terminal device; thefirst transmission mode (for example, the transmission mode 9) for thePDSCH transmission for the first downlink component carrier isconfigured for the terminal device; and the third information(supportedMIMO-CapabilityDL-r10) is included in the capabilityinformation (UECapabilityInformation), the fifth maximum number of thelayers assumed for determining the bit width for the RI is determined inaccordance with a smallest of (i) the number of configured first portsand (ii) the second maximum number of the layers indicated by the thirdinformation. Here, the first port is a transmit antenna port for aChanel State Information-Reference Signal (CSI-RS).

(2-6) In the second example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured for the terminal device; thefirst transmission mode (for example, the transmission mode 9) for thePDSCH transmission for the first downlink component carrier isconfigured for the terminal device; and the third information(supportedMIMO-CapabilityDL-r100) is not included in the capabilityinformation (UECapabilityInformation), the fifth maximum number of thelayers assumed for determining the bit width for the RI is determined inaccordance with a smallest of (i) the number of configured first portsand (ii) the first maximum number of the layers corresponding to thefirst information. Here, the first port is a transmit antenna port for aChanel State Information-Reference Signal (CSI-RS).

(2-7) In the second example, in a case that: the fifth information(LayersCount-v10xx) for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured for the terminal device; andthe second transmission mode (for example, the transmission mode 4) forthe PDSCH transmission for the first downlink component carrier isconfigured for the terminal device, the fifth maximum number of thelayers assumed for determining the bit width for the RI is determinedaccording to a smallest of (i) the number of second ports and (ii) thefirst maximum number of the layers. Here, the second port is a transmitantenna port for the Physical Broadcast CHannel (PBCH).

(2-8) In the second example, the reception unit 305 receives the RI onthe Physical Uplink Shared CHannel (PUSCH).

Hereinafter, a third example associated with the method of specifyingthe bit width for the RI in step S165 of FIG. 16 will be described. Thethird example is applied to the terminal device 1. In the third example,the third information (supportedMIMO-CapabilityDL-r10) is included inthe capability information (UECapabilityInformation). In the thirdexample, the capability information (UECapabilityInformation) may notneed to include the fourth information(supportedMIMO-CapabilityDL-v10xx).

(3-1) In the third example, the terminal device 1 includes: atransmission unit 107 configured to transmit a Rank Indicator (RI)determined by a terminal device, the RI corresponding to PhysicalDownlink Shared CHannel (PDSCH) transmission in a downlink componentcarrier corresponding to a first band in a first band combination andcorresponding to the number of layers; and a reception unit 105configured to receive the PDSCH. Here, a first maximum number of thelayers assumed for determining a bit width for the RI is based on thenumber of downlink component carriers configured in the first band inthe first band combination.

(3-2) In the third example, the first band combination includes only thefirst band.

(3-3) In the third example, the terminal device is configured with thetransmission mode 9 or 10 for the PDSCH transmission.

(3-4) In the third example, the transmission unit 107 transmitscapability information (UECapabilityInformation) including firstinformation (ca-BandwidthClassDL-r10), second information(supportedMIMO-CapabilityDL-r10), third information(ca-BandwidthClassDL-r10), and fourth information(supportedMIMO-CapabilityDL-r10). Here, the first information(ca-BandwidthClassDL-r10) indicates a first bandwidth class that is forthe first band in the first band combination and indicates a firstnumber of the downlink component carriers supported by the terminaldevice. Here, the second information (supportedMIMO-CapabilityDL-r10) isapplied to all of the first number of downlink component carrierscorresponding to the first band width class of the first band in thefirst band combination, and indicates the first maximum number of thelayers supported by the terminal device in the downlink. Here, the thirdinformation (ca-BandwidthClassDL-r10) indicates a second bandwidth classthat is for the first band in the first band combination and indicates asecond number of the downlink component carriers supported by theterminal device. Here, the fourth information(supportedMIMO-CapabilityDL-r10) is applied to all of the second numberof downlink component carriers corresponding to the second bandwidthclass of the first band in the first band combination, and indicates thesecond maximum number of the layers supported by the terminal device inthe downlink. Here, the third maximum number of the layers assumed fordetermining the bit width for the RI is given, based on whether thenumber of downlink component carriers configured in the first band inthe first band combination is either the first number or the secondnumber, by referring to any one of the first maximum number of thelayers and the second maximum number of the layers.

(3-5) In the third example, the transmission unit 107 transmits the RIon the Physical Uplink Shared CHannel (PUSCH).

(3-6) In the third example, in a case that the number of downlinkcomponent carriers configured in the first band in the first bandcombination is the first number, the third maximum number of the layersassumed for determining the bit width for the RI is the first maximumnumber of the layers. Here, in a case that the number of downlinkcomponent carriers configured in the first band in the first bandcombination is the second number, the third maximum number of the layersassumed for determining the bit width for the RI is the second maximumnumber of the layers.

Hereinafter, a fourth example associated with the method of specifyingthe bit width for the RI in step S165 of FIG. 16 will be described. Thefourth example is applied to the base station device 3. In the fourthexample, the third information (supportedMIMO-CapabilityDL-r10) isincluded in the capability information (UECapabilityInformation). In thefourth example, the capability information (UECapabilityInformation) maynot need to include the fourth information(supportedMIMO-CapabilityDL-v10xx).

(4-1) In the fourth example, the base station device 3 includes: areception unit 305 configured to receive, from a terminal device, a RankIndicator (RI) determined by the terminal device, the RI correspondingto Physical Downlink Shared CHannel (PDSCH) transmission in a downlinkcomponent carrier corresponding to a first band in a first bandcombination and corresponding to the number of layers; and atransmission unit 307 configured to transmit the PDSCH to the terminaldevice. Here, a first maximum number of the layers assumed fordetermining the bit width for the RI is based on the number of downlinkcomponent carriers to which the terminal device is configured in thefirst band in the first band combination.

(4-2) In the fourth example, the first band combination includes onlythe first band.

(4-3) In the fourth example, the terminal device is configured with thetransmission mode 9 or 10 for the PDSCH transmission.

(4-4) In the fourth example, the reception unit 305 receives, from theterminal device, capability information (UECapabilitylnformation)including first information (ca-BandwidthClassDL-r10), secondinformation (supportedMIMO-CapabilityDL-r10), third information(ca-BandwidthClassDL-r10), and fourth information(supportedMIMO-CapabilityDL-r10). Here, the first information(ca-BandwidthClassDL-r10) indicates a first bandwidth class that is forthe first band in the first band combination and indicates a firstnumber of the downlink component carriers supported by the terminaldevice. Here, the second information (supportedMIMO-CapabilityDL-r10) isapplied to all of the first number of downlink component carrierscorresponding to the first band width class of the first band in thefirst band combination, and indicates the first maximum number of thelayers supported by the terminal device in the downlink. Here, the thirdinformation (ca-BandwidthClassDL-r10) indicates a second bandwidth classthat is for the first band in the first band combination and indicates asecond number of the downlink component carriers supported by theterminal device. Here, the fourth information(supportedMIMO-CapabilityDL-r10) is applied to all of the second numberof downlink component carriers corresponding to the second bandwidthclass of the first band in the first band combination, and indicates thesecond maximum number of the layers supported by the terminal device inthe downlink. Here, the third maximum number of the layers assumed fordetermining the bit width for the RI is given, based on whether thenumber of downlink component carriers configured in the first band inthe first band combination is either the first number or the secondnumber, by referring to any one of the first maximum number of thelayers and the second maximum number of the layers.

(4-5) In the fourth example, the reception unit 305 receives the RI onthe Physical Uplink Shared CHannel (PUSCH).

(4-6) In the fourth example, in a case that the number of downlinkcomponent carriers configured in the first band in the first bandcombination is the first number, the third maximum number of the layersassumed for determining the bit width for the RI is the first maximumnumber of the layers. Here, in a case that the number of downlinkcomponent carriers configured in the first band in the first bandcombination is the second number, the third maximum number of the layersassumed for determining the bit width for the RI is the second maximumnumber of the layers.

Hereinafter, one example of a method of specifying a rate matching for acode block of a transport block in step S167 of FIG. 16 will bedescribed.

FIG. 17 is a diagram illustrating one example of a rate matchingaccording to the present embodiment. The rate matching is executed inS602 of FIG. 6. That is, the rate matching is applied to a code block ofa transport block.

One rate matching (S602) includes three interleaves (S1700), one bitcollection (S1701), and one bit selection and pruning (S2002). Threeinformation bit streams (d′_(k), d″_(k), d′″_(k)) are input to the onerate matching (S602) from the channel coding (S601). Each of the threeinformation bit streams (d′_(k), d″_(k), d′″_(k)) is interleaved inaccordance with a sub-block interleaver in the interleaves (S1700).Three output sequences (v′_(k), v″_(k), v′″_(k)) are obtained byinterleaving each of the three information bit streams (d′_(k), d″_(k),d′″_(k)).

A number C_(subblock) of a column of the subframe interleaver is 32. Anumber R_(subblock) of a row of the sub-block interleaver is a smallestinteger satisfying Inequality (1) below, where D is a bit number of eachof the information bit streams (d′_(k), d″_(k), d′″_(k)).D≤(R _(subblock) ×C _(subblock))  [Math. 1]

A bit number K_(Π) of each of the output sequences (v′_(k), v″_(k),v′″_(k)) of the subframe interleaver is given by Equation (2) below.K _(Π)=(R _(subblock) ×C _(subblock))  [Math. 2]

In the bit collection (S2001), w_(k) (virtual circular buffer) isobtained from three output sequences (v′_(k), v″_(k), v′″_(k)). w_(k) isgiven Equation (3) below. A bit number Kw of the w_(k) is three timesK_(Π).w _(k) =v′ _(k) for k=0, . . . ,K _(Π)−1w _(K) _(Π) _(+2k) =v _(k) ^(n) for k=0, . . . ,K _(Π)−1w _(K) _(Π) _(+2k+1) =v _(k) ^(m) for k=0, . . . ,K _(Π)−1  [Math. 3]

In the bit selection and pruning (S1702) of FIG. 17, a rate matchingoutput bit sequence e_(k) is obtained from w_(k). A bit number of therate matching output bit sequence e_(k) is E. FIG. 18 illustrates oneexample of the bit selection and pruning according to the presentembodiment. rv_(idx) of FIG. 18 is a redundancy version (RV) number fortransmission of a corresponding transport block. The RV number isindicated by information included in a DCI format. N_(cb) of FIG. 18 isa soft buffer size for a corresponding code block and is expressed bythe bit number. N_(cb) is given by Equation (4) below.

$\begin{matrix}{N_{cb} = {\min\left( {\left\lfloor \frac{N_{IR}}{C} \right\rfloor,K_{w}} \right)}} & \left\lbrack {{Math}.\mspace{14mu} 4} \right\rbrack\end{matrix}$

In the equation, C is the number of code blocks in which one transportblock is divided in the code block segmentation (S600) of FIG. 6. In theequation, N_(IR) is a soft buffer size for the corresponding transportblock and is expressed by the bit number. N_(IR) is given by Equation(5) below.

$\begin{matrix}{N_{IR} = \left\lfloor \frac{N_{soft}}{K_{C} \cdot K_{MIMO} \cdot {\min\left( {M_{DL\_ HARQ},M_{limit}} \right)}} \right\rfloor} & \left\lbrack {{Math}.\mspace{14mu} 5} \right\rbrack\end{matrix}$

In the equation, K_(MIMO) is 2 in a case that the terminal device 1 isconfigured to receive the PDSCH transmission based on the transmissionmode 3, 4, 8, 9, or 10. Otherwise, K_(MIMO) is 1. K_(MIMO) is same asthe maximum number of transport blocks that can be included by one PDSCHtransmission received based on the transmission mode with which theterminal device 1 is configured.

In the equation, M_(DL) _(_) _(HARQ) is a maximum number of downlinkHARQ processes managed concurrently in one corresponding serving cell.M_(DL) _(_) _(HARQ) may be 8 for an FDD serving cell. For a TDD servingcell, M_(DL) _(_) _(HARQ) may correspond to the uplink-downlinkconfiguration. In the equation, M_(limit) is 8.

In the equation, K_(c) is any one of 1, 3/2, 2, 3, and 5. A method ofconfiguring K_(c) will be described after a method of configuringN_(soft).

In the equation, N_(soft) is a total number of a UE category or a totalnumber of soft channel bits in accordance with a downlink UE category.N_(soft) is given by any one of the capability parameter ue-Category(without suffix), the capability parameter ue-Category-v1020, thecapability parameter ue-Category-v1170, and the capability parameterue-CategoryDL-r12.

N_(soft) may be specified based on (i) which one of the capabilityparameter ue-Category (without suffix), the capability parameterue-Category-v1020, the capability parameter ue-Category-v1170, and thecapability parameter ue-CategoryDL-r12 is transmitted, (ii) whether aparameter LayersCount-v10xx is received/configured, and/or (iii) whethera parameter altCQI-Table-r12 is received/configured.

In a case that the parameter altCQI-Table-r12 is not configured for theterminal device 1, the terminal device 1 derives a CQI, based on a firsttable indicating an association of a CQI with a combination of amodulation scheme and a coding rate for a single transport blocktransmitted on the PDSCH. In a case that the parameter altCQI-Table-r12is configured for the terminal device 1, the terminal device 1 derives aCQI, based on a second table indicating an association of a CQI with acombination of a modulation scheme and a coding rate for a singletransport block transmitted on the PDSCH. The first table may be a tabledesigned assuming that a 256 QAM is not applied to the PDSCH. The secondtable may be a table designed assuming that the 256 QAM is applied tothe PDSCH.

FIG. 19 is a diagram illustrating one example of a flow chart associatedwith a determination of the total number N_(soft) of the soft channelbits according to the present embodiment. The flow of FIG. 19 may beapplied to each of the downlink component carriers (cells). In a case ofsatisfying a first condition, first processing is performed. In a caseof not satisfying the first condition, the flow proceeds to a secondcondition. In a case of satisfying the second condition, secondprocessing is performed. In a case of not satisfying the secondcondition, the flow proceeds to a third condition. In a case ofsatisfying the third condition, third processing is performed. In a caseof not satisfying the third condition, fourth processing is performed.After performing the first processing, the second processing, the thirdprocessing, or the fourth processing, the flow associated with thedetermination of the total number N_(soft) of the soft channel bits isended.

In the first condition of FIG. 19, (i) in a case where the terminaldevice 1 signals the capability parameter ue-CategoryDL-r12 indicatingthe downlink UE category 0, or (ii) in a case where the terminal device1 signals the capability parameter ue-CategoryDL-r12 not indicating thedownlink UE category 0 and the terminal device 1 is configured with theparameter altCQI-Table-r12 for the downlink component carrier (cell) bythe higher layer (YES), N_(soft) is the total number of the soft channelbits in accordance with the downlink UE category indicated by thecapability parameter ue-CategoryDL-r12 (first processing).

In the second condition of FIG. 19, in a case where the terminal device1 signals the capability parameter ue-Category-v11a0 and in a case wherethe terminal device 1 is configured with the parameter altCQI-Table-r12for the downlink component carrier (cell) by the higher layer (YES),N_(soft) is the total number of the soft channel bits in accordance withthe UE category indicated by the capability parameter ue-Category0v11a0(second processing).

In the third condition of FIG. 19, in a case where the terminal device 1signals the capability parameter ue-Category-v1020 and in a case wherethe terminal device 1 is configured with the first transmission mode(for example, the transmission mode 9 or the transmission mode 10) forthe downlink component carrier (cell) (YES), N_(soft) is the totalnumber of the soft channel bits in accordance with the UE categoryindicated by the capability parameter ue-Category-v1020 (thirdprocessing). Here, the terminal device 1 may or may not signal thecapability parameter ue-Category-v1170.

In the third condition of FIG. 19, in a case where the terminal device 1signals the capability parameter ue-Category-v1020 and in a case wherethe terminal device 1 is configured with the parameter LayersCount-v10xxfor the downlink component carrier (cell) by the higher layer (YES),N_(soft) is the total number of the soft channel bits in accordance withthe UE category indicated by the capability parameter ue-Category-v1020(first processing). Here, the terminal device 1 may be configured with atransmission mode other than the first transmission mode. Here, theterminal device 1 may or may not signal the capability parameterue-Category-v1170.

In a case of not satisfying the first condition, the second condition,and the third condition of FIG. 19, N_(soft) is the total number of thesoft channel bits in accordance with the UE category indicated by thecapability parameter ue-Category (without suffix) (fourth processing).For example, in a case where the terminal device 1 signals thecapability parameter ue-Category-v11a0, the capability parameterue-Category-v1120, the capability parameter ue-Category-v1020, and thecapability parameter ue-Category (without suffix), in a case where theterminal device 1 is not configured with the parameter altCQI-Table-r12for the downlink component carrier (cell) by the higher layer, in a casewhere the terminal device 1 is not configured with the parameterLayersCount-v10xx for the downlink component carrier (cell) by thehigher layer, and in a case where the terminal device 1 is configuredwith a transmission mode other than the first transmission mode,N_(soft) is the total number of the soft channel bits in accordance withthe UE category indicated by the capability parameter ue-Category(without suffix). Furthermore, for example, in a case where the terminaldevice 1 signals the capability parameter ue-Category-v1120, thecapability parameter ue-Category-v1020, and the capability parameterue-Category (without suffix), in a case where the terminal device 1 isnot configured with the parameter LayersCount-v100xx for the downlinkcomponent carrier (cell) by the higher layer, and in a case where theterminal device 1 is configured with a transmission mode other than thefirst transmission mode, N_(soft) is the total number of the softchannel bits in accordance with the UE category indicated by thecapability parameter ue-Category (without suffix).

FIG. 20 illustrates one example of a method of configuring K_(c)according to the present embodiment. K_(c) is given based on (i)N_(soft) specified in FIG. 19, (ii) whether the terminal device 1 isconfigured with the parameter altCQI-Table-r12 for the downlinkcomponent carrier (cell) by the higher layer, and/or (iii) the maximumnumber of layers for the downlink component carrier (cell). Here, themaximum number of layers may be given by referring to (i) the number oflayers supported, for the downlink component carrier (cell), by a PDSCHtransmission scheme corresponding to the transmission mode with whichthe terminal device 1 is configured and/or (ii) the maximum number oflayers assumed for specifying the bit width for the RI in S165 of FIG.16. For example, the maximum number of layers may be given in accordancewith a smallest of (i) the number of layers supported, for the downlinkcomponent carrier (cell), by the PDSCH transmission scheme correspondingto the transmission mode with which the terminal device 1 is configuredand (ii) the maximum number of layers assumed for specifying the bitwidth for the RI in S165 of FIG. 16.

That is, the soft buffer size N_(cb) for the corresponding code blockand the rate matching for the corresponding code block may be given byreferring to some or all of (i) to (v) below:

(i) which one of the capability parameter ue-Category (without suffix),the capability parameter ue-Category-v1020, the capability parameterue-Category-v1170, and the capability parameter ue-CategoryDL-r12 istransmitted;

(ii) whether the parameter LayersCount-v10xx for the downlink componentcarrier is received/configured;

(iii) whether the parameter altCQI-Table-r12 for the downlink componentcarrier is received/configured;

(iv) the number of layers supported, for the downlink component carrier,by the PDSCH transmission scheme corresponding to the transmission modewith which the terminal device 1 is configured; and

(v) the maximum number of layers assumed for specifying the bit widthfor the RI

Hereinafter, a fifth example associated with the method of specifying arate matching for a code block size of the transport block in step S167of FIG. 16 will be described. The fifth example is applied to theterminal device 1.

(5-1) In the fifth example, the terminal device 1 includes: atransmission unit 107 configured to transmit a Rank Indicator (RI) forPhysical Downlink Shared CHannel (PDSCH) transmission; a reception unit105 configured to receive first information (anRRCConnectionReconfiguration message) used for determining a firstmaximum number of layers that is a first maximum number assumed fordetermining a bit width for the RI and to receive a transport block onthe PDSCH, and a decoding unit 1051 configured to decode a code block ofthe transport block. Here, a rate matching for the code block is basedat least on a soft buffer size for the code block. Here, the soft buffersize for the code block is based at least on the first information(RRCConnectionReconfiguration message) used for determining the firstmaximum number of the layers.

(5-2) In the fifth example, the transmission unit 107 transmits the RIon a Physical Uplink Shared CHannel (PUSCH).

(5-3) In the fifth example, the terminal device 1 is configured with aprescribed transmission mode associated with the PDSCH transmission.

(5-4) In the fifth example, the transmission unit 107 transmitscapability information (UECapabilityInformation) including secondinformation (ue-Category (without suffix)) and third information(ue-Category-v1020). Here, the second information (ue-Category (withoutsuffix)) indicates a second maximum number of the layers supported bythe terminal device in a downlink, and a first UE category correspondingto a first total number of soft channel bits capable of being utilizedfor Hybrid Automatic Repeat reQuest (HARQ) processing in the downlink.Here, the third information (ue-Category-v1020) indicates a thirdmaximum number of the layers supported by the terminal device in thedownlink, and a second UE category corresponding to a second totalnumber of soft channel bits capable of being utilized for HybridAutomatic Repeat reQuest (HARQ) processing in the downlink. Here, thesoft buffer size for the code block is given by referring to any one ofthe first total number and the second total number, based on whether thefirst information (RRCConnectionReconfiguration message) used fordetermining the first maximum number of the layers indicates a fourthmaximum number of the layers. That is, the soft buffer size for the codeblock is given by referring to any one of the first total number and thesecond total number, based on whether the first information used fordetermining the first maximum number of the layers is configured to avalue indicating the fourth maximum number of the layers.

(5-5) In the fifth example, in a case that the first information(RRCConnectionReconfiguration message) used for determining the firstmaximum number of the layers indicates the fourth maximum number of thelayers, the soft buffer size for the code block is given by referring tothe first total number. Here, in a case that the first information(RRCConnectonReconfiguration message) used for determining the firstmaximum number of the layers does not indicate the fourth maximum numberof the layers, the soft buffer size for the code block is given byreferring to the second total number. Here, “the first information(RRCConnectionReconfiguration message) does not indicate the fourthmaximum number of the layers” includes “the parameter LayersCount-v100xxis not included in the first information (RRCConnectionReconfigurationmessage)”. That is, in a case that the first information used fordetermining the first maximum number of the layers is configured to thevalue indicating the fourth maximum number of the layers, the softbuffer size for the code block is given by referring to the first totalnumber, and in a case that the first information used for determiningthe first maximum number of the layers is not configured by the valueindicating the fourth maximum number of the layers, the soft buffer sizefor the code block is given by referring to the second total number.

(5-6) In the fifth example, in a case that the first information(RRCConnectionReconfiguration message) used for determining the firstmaximum number of the layers indicates the fourth maximum number of thelayers, the first maximum number of the layers is given by referring tothe fourth maximum number of the layers. Here, the “first information(RRCConnectionReconfiguration message) indicates the fourth maximumnumber of the layers” includes “the parameter LayersCount-v100xxincluded in the first information (RRCConnectionReconfiguration message)indicates the fourth maximum number of the layers”. That is, in a casethat the first information is received, the first maximum number of thelayers is given by referring to the first information.

(5-7) In the fifth example, in a case that the first information(RRCConnectionReconfiguration message) used for determining the firstmaximum number of the layers does not indicate the fourth maximum numberof the layers, the first maximum number of the layers is given byreferring to any one of a plurality of maximum numbers of layersincluding at least the second maximum number of the layers and the thirdmaximum number of the layers. That is, in a case that the firstinformation is not received, the first maximum number of the layers isgiven by referring to any one of the second information and the thirdinformation.

Hereinafter, a sixth example associated with the method of specifyingthe rate matching for the code block size of the transport block in stepS167 of FIG. 16 will be described. The sixth example is applied to thebase station device 3.

(6-1) In the sixth example, the base station device 3 includes: areception unit 305 configured to receive a Rank Indicator (RI) forPhysical Downlink Shared CHannel (PDSCH) transmission from a terminaldevice; a transmission unit 307 configured to transmit, to the terminaldevice, first information (RRCConnectionReconfiguration message) used bythe terminal device for determining a first maximum number of layersassumed by the terminal device for determining a bit width for the RIand to transmit a transport block to the terminal device on the PDSCH;and a coding unit 3071 configured to code a code block of the transportblock. Here, the rate matching for the coded code block is based atleast on the soft buffer size for the code block. Here, the soft buffersize for the code block is based at least on first information (anRRCConnectionReconfiguration message) used by the terminal device fordetermining the first maximum number of the layers.

(6-2) In the sixth example, the reception unit 305 receives the RI fromthe terminal device on a Physical Uplink Shared CHannel (PUSCH).

(6-3) In the sixth example, the terminal device 1 is configured with aprescribed transmission mode associated with the PDSCH transmission.

(6-4) In the sixth example, the reception unit 305 receives capabilityinformation (UECapabilityInformation) including second information(ue-Category (without suffix)) and third information (ue-Category-v1020)from the terminal device. Here, the second information (ue-Category(without suffix)) indicates the second maximum number of the layerssupported by the terminal device in a downlink, and a first UE categorycorresponding to a first total number of soft channel bits capable ofbeing utilized for Hybrid Automatic Repeat reQuest (HARQ) processing inthe downlink. Here, the third information (ue-Category-v1020) indicatesthe third maximum number of the layers supported by the terminal devicein the downlink, and a second UE category corresponding to a secondtotal number of soft channel bits capable of being utilized for HybridAutomatic Repeat reQuest (HARQ) processing in the downlink. Here, thesoft buffer size for the code block is given by referring to any one ofthe first total number and the second total number, based on whether thefirst information (RRCConnectionReconfiguration message) used by theterminal device for determining the first maximum number of the layersindicates the fourth maximum number of the layers. That is, the softbuffer size for the code block is given by referring to any one of thefirst total number and the second total number, based on whether thefirst information used for determining the first maximum number of thelayers is configured to a value indicating the fourth maximum number ofthe layers.

(6-5) In the sixth example, in a case that the first information(RRCConnectionReconfiguration message) used by the terminal device fordetermining the first maximum number of the layers indicates the fourthmaximum number of the layers, the soft buffer size for the code block isgiven by referring to the first total number. Here, in a case that thefirst information (RRCConnectionReconfiguration message) used by theterminal device for determining the first maximum number of the layersdoes not indicate the fourth maximum number of the layers, the softbuffer size for the code block is given by referring to the second totalnumber. That is, in a case that the first information used fordetermining the first maximum number of the layers is configured to thevalue indicating the fourth maximum number of the layers, the softbuffer size for the code block is given by referring to the first totalnumber, and in a case that the first information used for determiningthe first maximum number of the layers is not configured to the valueindicating the fourth maximum number of the layers, the soft buffer sizefor the code block is given by referring to the second total number.

(6-6) In the sixth example, in a case that the first information(RRCConnectonReconfiguration message) used by the terminal device fordetermining the first maximum number of the layers indicates the fourthmaximum number of the layers, the first maximum number of the layers isgiven by referring to the fourth maximum number of the layers. That is,in a case that the first information is received, the first maximumnumber of the layers is given by referring to the first information.

(6-7) In the sixth example, in a case that the first information(RRCConnectionReconfiguration message) used by the terminal device fordetermining the first maximum number of the layers does not indicate thefourth maximum number of the layers, the first maximum number of thelayers is given by referring to any one of a plurality of maximumnumbers of the layers including at least the second maximum number ofthe layers and the third maximum number of the layers. That is, in acase that the first information is not received, the first maximumnumber of the layers is given by referring to any one of the secondinformation and the third information.

In S169 of FIG. 16, soft channel bits of a code block of a transportblock stored by the terminal device 1 are based on the soft buffer sizeN_(cb) for the code block of the transport block. In a case that theterminal device 1 fails to decode the code block of the transport block,the terminal device 1 stores the received soft channel bits at leastcorresponding to a range of <w_(k), w_(k+1), . . . ,w_((k+nSB−1) mod Ncb)>. k of <w_(k), w_(k+1), . . . ,w_((k+nSB−1) mod Ncb)> is determined by the terminal device 1. Here, indetermination of k of <w_(k), w_(k+1), . . . , w_((k+nSB−1)mod NcB)>, itis preferable that the terminal device 1 prioritize storing soft channelbits corresponding to a lower value of k.

FIG. 21 is a diagram illustrating one example of a range of <w_(k),w_(k)+1, . . . , w_((k+nSB−1) mod Ncb)> according to the presentembodiment. Here, n_(SB) is given by referring to the soft buffer sizeN_(cb) for a code block of a transport block. n_(SB) is given byEquation (6) below.

$\begin{matrix}{n_{SB} = {\min\left( {N_{cb},\left\lfloor \frac{N_{soft}^{\prime}}{C \cdot N_{DL\_ cells} \cdot K_{MIMO} \cdot {\min\left( {M_{DL\_ HARQ},M_{limit}} \right)}} \right\rfloor} \right)}} & \left\lbrack {{Math}.\mspace{14mu} 6} \right\rbrack\end{matrix}$

In the equation, C is defined in Equation (4). In the equation,K_(MIMO), M_(DL) _(_) _(HARQ), and M_(limit) are defined in Equation 5.In the equation, N_(DL) _(_) _(cells) is the number of downlinkcomponent carriers (cells) configured for the terminal device 1. In theequation, N′_(soft) is the total number of soft channel bits inaccordance with the UE category or the downlink UE category. N′_(soft)is given by any one of the capability parameter ue-Category (withoutsuffix), the capability parameter ue-Category-v1020, the capabilityparameter ue-Category 1170, and the capability parameterue-CategoryDL-r12. Note that N_(soft) and N′_(soft) are separatelydefined.

FIG. 22 is a diagram illustrating one example of a flow chart associatedwith a determination of the total number N′_(soft) of the soft channelbits according to the present embodiment. The flow of FIG. 22 may beapplied to each of the downlink component carriers (cells). In a case ofsatisfying a fourth condition, fifth processing is performed. In a caseof not satisfying the fourth condition, the flow proceeds to the fifthcondition. In a case of satisfying a fifth condition, sixth processingis performed. In a case of not satisfying the fifth condition, the flowproceeds to a sixth condition. In a case of satisfying the sixthcondition, seventh processing is performed. In a case of not satisfyingthe sixth condition, the flow proceeds to a seventh condition. In a caseof satisfying the seventh condition, eighth processing is performed. Ina case of not satisfying the seventh condition, ninth processing isperformed. After performing the fifth processing, the sixth processing,the seventh processing, the eighth processing or the ninth processing,the flow associated with the determination of the total number N′_(soft)of the soft channel bits is ended.

In the fourth condition of FIG. 22, in a case where the terminal device1 signals the capability parameter ue-CategoryDL-r12 (YES), N_(soft) isthe total number of soft channel bits in accordance with the downlink UEcategory indicated by the capability parameter ue-CategoryDL-r12 (fifthprocessing).

In the fifth condition of FIG. 22, in a case where the terminal device 1signals the capability parameter ue-Category-v11a0 and does not signalthe capability parameter ue-CategoryDL-r12 (YES), N_(soft) is the totalnumber of soft channel bits in accordance with the UE category indicatedby the capability parameter ue-Category-v11a0 (sixth processing).

In the sixth condition of FIG. 22, in a case where the terminal device 1signals the capability parameter ue-Category-v1170 and does not signalthe capability parameter ue-Category-v11a0 and the capability parameterue-CategoryDL-r12 (YES), N_(soft) is the total number of soft channelbits in accordance with the UE category indicated by the capabilityparameter ue-Category-v1170 (seventh processing).

In the seventh condition of FIG. 22, in a case where the terminal device1 signals the capability parameter ue-Category-v1020 and does not signalthe capability parameter ue-Category-v1170, the capability parameterue-Category-v11a0, and the capability parameter ue-CategoryDL-r12 (YES),N_(soft) is the total number of soft channel bits in accordance with theUE category indicated by the capability parameter ue-Category-v1020(eighth processing).

In the seventh condition of FIG. 22, in a case where the terminal device1 signals the capability parameter ue-Category (without suffix) and doesnot signal the capability parameter ue-Category-v1020, the capabilityparameter ue-Category-v1170, the capability parameter ue-Category-v11a0,and the capability parameter ue-CategoryDL-r12 (NO), N_(soft) is thetotal number of soft channel bits in accordance with the UE categoryindicated by the capability parameter ue-Category (without suffix)(ninth processing).

That is, in a case that the terminal device 1 fails to decode a codeblock of a transport block, soft channel bits to be stored by theterminal device 1 may be given by referring to some or all of (i) to (v)below:

(i) which one of the capability parameter ue-Category (without suffix),the capability parameter ue-Category-v1020, the capability parameterue-Category-v1170, and the capability parameter ue-CategoryDL-r12 istransmitted;

(ii) whether the parameter LayersCount-v10xx for the downlink componentcarrier is received/configured;

(iii) whether the parameter altCQI-Table-r12 for the downlink componentcarrier is received/configured;

(iv) the number of layers supported by a PDSCH transmission schemecorresponding to a transmission mode with which the terminal device 1 isconfigured for the downlink component carrier; and

(v) the maximum number of layers assumed for specifying the bit widthfor an RI

Hereinafter, a seventh example associated with a method of storing thesoft channel bits for the code block size of the transport block in stepS169 of FIG. 16 will be described. The seventh example is applied to theterminal device 1.

(7-1) In the seventh example, the terminal device 1 includes: atransmission unit 107 configured to transmit a Rank Indicator (RI) forPhysical Downlink Shared CHannel (PDSCH) transmission; a reception unit105 configured to receive first information (anRRCConnectionReconfiguration message) used for determining a firstmaximum number of layers that is a first maximum number assumed fordetermining a bit width for the RI and to receive a transport block onthe PDSCH, and a decoding unit 1051 configured to decode a code block ofthe transport block. Here, in a case that the decoding unit 1051 failsto decode the code block, the decoding unit 1051 stores at least softchannel bits corresponding to a range of prescribed soft channel bitsout of soft channel bits of the code block. Here, the prescribed softchannel bits are based on the soft buffer size for the code block. Here,the soft buffer size for the code block is based at least on the firstinformation (RRCConnectionReconfiguration message) used for determiningthe first maximum number of the layers.

(7-2) In the seventh example, the transmission unit 107 transmits the RIon the Physical Uplink Shared CHannel (PUSCH).

(7-3) In the seventh example, the terminal device 1 is configured with afirst transmission mode for the PDSCH transmission.

(7-4) In the seventh example, the transmission unit 107 transmitscapability information (UECapabilitylnformation) including secondinformation (ue-Category (without suffix)) and third information(ue-Category-v1020). Here, the second information (ue-Category (withoutsuffix)) indicates the second maximum number of the layers supported bythe terminal device in a downlink, and a first UE category correspondingto a first total number of soft channel bits capable of being utilizedfor Hybrid Automatic Repeat reQuest (HARQ) processing in the downlink.Here, the third information (ue-Category-v1020) indicates the thirdmaximum number of the layers supported by the terminal device in thedownlink, and a second UE category corresponding to a second totalnumber of soft channel bits capable of being utilized for HybridAutomatic Repeat reQuest (HARQ) processing in the downlink. Here, thesoft buffer size for the code block is given by referring to any one ofthe first total number and the second total number, based on whether thefirst information (RRCConnectionReconfiguration message) used fordetermining the first maximum number of the layers indicates the fourthmaximum number of the layers. That is, the soft buffer size for the codeblock is given by referring to any one of the first total number and thesecond total number, based on whether the first information used fordetermining the first maximum number of the layers is configured to avalue indicating the fourth maximum number of the layers.

(7-5) In the seventh example, in a case that the first information(RRCConnectionReconfiguration message) used for determining the firstmaximum number of the layers indicates the fourth maximum number of thelayers, the soft buffer size for the code block is given by referring tothe first total number. Here, in a case that the first information(RRCConnectonReconfiguration message) used for determining the firstmaximum number of the layers does not indicate the fourth maximum numberof the layers, the soft buffer size for the code block is given byreferring to the second total number. Here, “the first information(RRCConnectionReconfiguration message) does not indicate the fourthmaximum number of the layers” includes “the parameter LayersCount-v100xxis not included in the first information (RRCConnectionReconfigurationmessage)”. That is, in a case that the first information used fordetermining the first maximum number of the layers is configured to thevalue indicating the fourth maximum number of the layers, the softbuffer size for the code block is given by referring to the first totalnumber, and in a case that the first information used for determiningthe first maximum number of the layers is not configured to the valueindicating the fourth maximum number of the layers, the soft buffer sizefor the code block is given by referring to the second total number.

(7-6) In the seventh example, in a case that the first information(RRCConnectionReconfiguration message) used for determining the firstmaximum number of the layers indicates the fourth maximum number of thelayers, the first maximum number of the layers is given by referring tothe fourth maximum number of the layers. Here, the “first information(RRCConnectionReconfiguration message) indicates the fourth maximumnumber of the layers” includes “the parameter LayersCount-v10xx includedin the first information (RRCConnectionReconfiguration message)indicates the fourth maximum number of the layers”. That is, in a casethat the first information is received, the first maximum number of thelayers is given by referring to the first information.

(7-7) In the seventh example, in a case that the first information(RRCConnectionReconfiguration message) used for determining the firstmaximum number of the layers does not indicate the fourth maximum numberof the layers, the first maximum number of the layers is given byreferring to any one of a plurality of maximum numbers of the layersincluding at least the second maximum number of the layers and the thirdmaximum number of the layers. That is, in a case that the firstinformation is not received, the first maximum number of the layers isgiven by referring to any one of the second information and the thirdinformation.

The present embodiment has been described in detail with references tothe first example to the seventh example and FIG. 1 to FIG. 22, butvarious modifications are possible within the scope indicated in thefirst example to the seventh example and FIG. 1 to FIG. 22, and thetechnical means/method that are made by suitably combining technicalmeans/methods disclosed each in the different examples and drawings arealso included in the technical scope of the present invention.

Therefore, the terminal device 1 can efficiently communicate with thebase station device 3, even in a case where not knowing the release andthe version of LTE supported by the base station device 3. Furthermore,the base station device 3 can efficiently communicate with the terminaldevice 1, even in a case where not knowing the release and the versionof LTE supported by the terminal device 1.

A program running on each of the base station device 3 and the terminaldevice 1 according to the present invention may be a program thatcontrols a Central Processing Unit (CPU) and the like (a program forcausing a computer to operate) in such a manner as to realize thefunctions according to the above-described embodiments of the presentinvention. The information handled in these devices is temporarilystored in a Random Access Memory (RAM) while being processed.Thereafter, the information is stored in various types of Read OnlyMemory (ROM) such as a flash ROM and a Hard Disk Drive (HDD) and whennecessary, is read by the CPU to be modified or rewritten.

Moreover, the terminal device 1 and the base station device 3 accordingto the above-described embodiments may be partially realized by acomputer. This configuration may be realized by recording a program forrealizing such control functions on a computer-readable medium andcausing a computer system to read the program recorded on the recordingmedium for execution.

The “computer system” refers to a computer system built into theterminal device 1 or the base station device 3, and the computer systemincludes an OS and hardware components such as a peripheral device.Furthermore, the “computer-readable recording medium” refers to aportable medium such as a flexible disk, a magneto-optical disk, a ROM,and a CD-ROM, and a storage device such as a hard disk built into thecomputer system.

Moreover, the “computer-readable recording medium” may include a mediumthat dynamically retains the program for a short period of time, such asa communication line that is used to transmit the program over a networksuch as the Internet or over a communication circuit such as a telephonecircuit, and a medium that retains, in that case, the program for afixed period of time, such as a volatile memory within the computersystem which functions as a server or a client. Furthermore, the programmay be configured to realize some of the functions described above, andalso may be configured to be capable of realizing the functionsdescribed above in combination with a program already recorded in thecomputer system.

Furthermore, the base station device 3 according to the above-describedembodiments can be realized as an aggregation (a device group)constituted of multiple devices. Devices constituting the device groupmay be each equipped with some or all portions of each function or eachfunctional block of the base station device 3 according to theabove-described embodiments. It is only required that the device groupitself include general functions or general functional blocks of thebase station device 3. Furthermore, the terminal device 1 according tothe above-described embodiments can also communicate with the basestation device as the aggregation.

Furthermore, the base station device 3 according to the above-describedembodiments may be an Evolved Universal Terrestrial Radio Access Network(EUTRAN). Furthermore, the base station device 3 according to theabove-described embodiments may have some or all portions of thefunction of a node higher than an eNodeB.

Furthermore, some or all portions of each of the terminal device 1 andthe base station device 3 according to the above-described embodimentsmay be realized as an LSI that is a typical integrated circuit or may berealized as a chip set. The functional blocks of each of the terminaldevice 1 and the base station device 3 may be individually realized as achip, or some or all of the functional blocks may be integrated into achip. Furthermore, the circuit integration technique is not limited tothe LSI, and the integrated circuit may be realized with a dedicatedcircuit or a general-purpose processor. Furthermore, in a case wherewith advances in semiconductor technology, a circuit integrationtechnology with which an LSI is replaced appears, it is also possible touse an integrated circuit based on the technology.

Furthermore, according to the above-described embodiment, the terminaldevice is described as one example of a terminal device or acommunication device, but the present invention is not limited to this,and can be applied to a fixed-type or a stationary-type electronicapparatus installed indoors or outdoors, for example, a terminal deviceor a communication device, such as an audio-video (AV) apparatus, akitchen apparatus, a cleaning or washing machine, an air-conditioningapparatus, office equipment, a vending machine, and other householdapparatuses.

The embodiments of the present invention have been described in detailabove referring to the drawings, but the specific configuration is notlimited to the embodiments and includes, for example, an amendment to adesign that falls within the scope that does not depart from the gist ofthe present invention. Furthermore, various modifications are possiblewithin the scope of the present invention defined by claims, andembodiments that are made by suitably combining technical meansdisclosed according to the different embodiments are also included inthe technical scope of the present invention. Furthermore, aconfiguration in which a constituent element that achieves the sameeffect is substituted for the one that is described according to theembodiments is also included in the technical scope of the presentinvention.

INDUSTRIAL APPLICABILITY

The present invention can be applied to terminal devices orcommunication devices such as a mobile phone, a personal computer, atablet computer, an audio-video (AV) apparatus, a kitchen apparatus, acleaning or washing machine, an air-conditioning apparatus, officeequipment, a vending machine, and other household apparatuses.

DESCRIPTION OF REFERENCE NUMERALS

-   1 (1A, 1B, 1C) Terminal device-   3 Base station device-   101 Higher layer processing unit-   103 Control unit-   105 Reception unit-   107 Transmission unit-   301 Higher layer processing unit-   303 Control unit-   305 Reception unit-   307 Transmission unit-   1011 Radio resource control unit-   1013 Scheduling information interpretation unit-   1015 CSI report control unit-   3011 Radio resource control unit-   3013 Scheduling unit-   3015 CSI report control unit

The invention claimed is:
 1. A terminal device, comprising: transmissioncircuitry configured to transmit a Rank Indicator (RI) determined by theterminal device, the RI corresponding to a number of useful layers andcorresponding to Physical Downlink Shared CHannel (PDSCH) transmissionin a first downlink component carrier corresponding to a first bandwidthclass of a first band in a first band combination; and receptioncircuitry configured to receive the PDSCH, wherein the transmissioncircuitry is configured to transmit capability information includingfirst information, second information, and/or third information, thereception circuitry is configured to receive fifth information for thefirst downlink component carrier corresponding to the first bandwidthclass of the first band in the first band combination, the firstinformation indicates a UE category corresponding to a first maximumnumber of the layers supported by the terminal device in a downlink, thesecond information indicates the first bandwidth class being for thefirst band in the first band combination and corresponding to a numberof downlink component carriers supported by the terminal device, thethird information is applied to all of one or more downlink componentcarriers corresponding to the first bandwidth class of the first band inthe first band combination, and indicates a second maximum number of thelayers supported by the terminal device in the downlink, the fifthinformation indicates a fourth maximum number of the layers, in a casethat the fifth information for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured, a fifth maximum number of thelayers assumed for determining a bit width for the RI is given byreferring to any one of the first information and the third information,and in a case that the fifth information for the first downlinkcomponent carrier corresponding to the first bandwidth class of thefirst band in the first band combination is configured, the fifthmaximum number of the layers assumed for determining the bit width forthe RI is given by referring to the fifth information.
 2. The terminaldevice according to claim 1, wherein in a case that the fifthinformation for the first downlink component carrier corresponding tothe first bandwidth class of the first band in the first bandcombination is configured, and a second transmission mode for the PDSCHtransmission is configured for the first downlink component carrier, thefifth maximum number of the layers assumed for determining the bit widthfor the RI is determined according to at least a third maximum number ofthe layers indicated by the fifth information.
 3. The terminal deviceaccording to claim 1, wherein in a case that the fifth information forthe first downlink component carrier corresponding to the firstbandwidth class of the first band in the first band combination is notconfigured, a first transmission mode for the PDSCH transmission isconfigured for the first downlink component carrier, and the thirdinformation is included in the capability information, the fifth maximumnumber of the layers assumed for determining the bit width for the RI isdetermined according to a minimum of (i) a configured number of firstports and (ii) the second maximum number of the layers indicated by thethird information, and the first port is a transmit antenna port for aChanel State Information-Reference Signal (CSI-RS).
 4. The terminaldevice according to claim 1, wherein in a case that the fifthinformation for the first downlink component carrier corresponding tothe first bandwidth class of the first band in the first bandcombination is not configured, a first transmission mode for the PDSCHtransmission is configured for the first downlink component carrier, andthe third information is not included in the capability information, thefifth maximum number of the layers assumed for determining the bit widthfor the RI is determined according to a minimum of (i) a configurednumber of first ports and (ii) the first maximum number of the layerscorresponding to the first information, and the first port is a transmitantenna port for a Chanel State Information-Reference Signal (CSI-RS).5. The terminal device according to claim 1, wherein in a case that thefifth information for the first downlink component carrier correspondingto the first bandwidth class of the first band in the first bandcombination is not configured, and a second transmission mode for thePDSCH transmission is configured for the first downlink componentcarrier, the fifth maximum number of the layers assumed for determiningthe bit width for the RI is determined according to a minimum of (i) anumber of second ports and (ii) the first maximum number of the layerscorresponding to the first information, and the second port is atransmit antenna port for a Physical Broadcast CHannel (PBCH).
 6. Theterminal device according to claim 1, wherein the transmission circuitryis configured to transmit the RI on a Physical Uplink Shared CHannel(PUSCH).
 7. A base station device, comprising: reception circuitryconfigured to receive, from a terminal device, a Rank Indicator (RI)determined by the terminal device, the RI corresponding to a number ofuseful layers and corresponding to Physical Downlink Shared CHannel(PDSCH) transmission in a first downlink component carrier correspondingto a first bandwidth class of a first band in a first band combination;and transmission circuitry configured to transmit the PDSCH to theterminal device, wherein the reception circuitry is configured toreceive, from the terminal device, capability information includingfirst information, second information, and/or third information, thetransmission circuitry is configured to transmit, to the terminaldevice, fifth information for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination, the first information indicates a UE categorycorresponding to a first maximum number of the layers supported by theterminal device in a downlink, the second information indicates thefirst bandwidth class being for the first band in the first bandcombination and corresponding to a number of downlink component carrierssupported by the terminal device, the third information is applied toall of one or more downlink component carriers corresponding to thefirst bandwidth class of the first band in the first band combination,and indicates a second maximum number of the layers supported by theterminal device in the downlink, the fifth information indicates afourth maximum number of the layers, in a case that the fifthinformation for the first downlink component carrier corresponding tothe first bandwidth class of the first band in the first bandcombination is not configured for the terminal device, a fifth maximumnumber of the layers assumed for determining a bit width for the RI isgiven by referring to any one of the first information and the thirdinformation, and in a case that the fifth information for the firstdownlink component carrier corresponding to the first bandwidth class ofthe first band in the first band combination is configured for theterminal device, the fifth maximum number of the layers assumed fordetermining the bit width for the RI is given by referring to the fifthinformation.
 8. The base station device according to claim 7, wherein ina case that the fifth information for the first downlink componentcarrier corresponding to the first bandwidth class of the first band inthe first band combination is configured for the terminal device, and asecond transmission mode for the PDSCH transmission for the firstdownlink component carrier is configured for the terminal device, thefifth maximum number of the layers assumed for determining the bit widthfor the RI is determined according to at least a third maximum number ofthe layers indicated by the fifth information.
 9. The base stationdevice according to claim 7, wherein in a case that the fifthinformation for the first downlink component carrier corresponding tothe first bandwidth class of the first band in the first bandcombination is not configured for the terminal device, a firsttransmission mode for the PDSCH transmission for the first downlinkcomponent carrier is configured for the terminal device, and the thirdinformation is included in the capability information, the fifth maximumnumber of the layers assumed for determining the bit width for the RI isdetermined according to a minimum of (i) a configured number of firstports and (ii) the second maximum number of the layers indicated by thethird information, and the first port is a transmit antenna port for aChanel State Information-Reference Signal (CSI-RS).
 10. The base stationdevice according to claim 7, wherein in a case that the fifthinformation for the first downlink component carrier corresponding tothe first bandwidth class of the first band in the first bandcombination is not configured for the terminal device, a firsttransmission mode for the PDSCH transmission for the first downlinkcomponent carrier is configured for the terminal device, and the thirdinformation is not included in the capability information, the fifthmaximum number of the layers assumed for determining the bit width forthe RI is determined according to a minimum of (i) a configured numberof first ports and (ii) the first maximum number of the layerscorresponding to the first information, and the first port is a transmitantenna port for a Chanel State Information-Reference Signal (CSI-RS).11. The base station device according to claim 7, wherein in a case thatthe fifth information for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is not configured for the terminal device, and asecond transmission mode for the PDSCH transmission for the firstdownlink component carrier is configured for the terminal device, thefifth maximum number of the layers assumed for determining the bit widthfor the RI is determined according to a minimum of (i) a number ofsecond ports and (ii) the first maximum number of the layerscorresponding to the first information, and the second port is atransmit antenna port for a Physical Broadcast CHannel (PBCH).
 12. Thebase station device according to claim 7, wherein the receptioncircuitry is configured to receive the RI on a Physical Uplink SharedCHannel (PUSCH).
 13. A communication method used for a terminal device,the method comprising the steps of: transmitting a Rank Indicator (RI)determined by the terminal device, the RI corresponding to a number ofuseful layers and corresponding to Physical Downlink Shared CHannel(PDSCH) transmission in a first downlink component carrier correspondingto a first bandwidth class of a first band in a first band combination;receiving the PDSCH; transmitting capability information including firstinformation, second information, and/or third information; and receivingfifth information for the first downlink component carrier correspondingto the first bandwidth class of the first band in the first bandcombination, wherein the first information indicates a UE categorycorresponding to a first maximum number of the layers supported by theterminal device in a downlink, the second information indicates thefirst bandwidth class being for the first band in the first bandcombination and corresponding to a number of downlink component carrierssupported by the terminal device, the third information is applied toall of one or more downlink component carriers corresponding to thefirst bandwidth class of the first band in the first band combination,and indicates a second maximum number of the layers supported by theterminal device in the downlink, the fifth information indicates afourth maximum number of the layers, in a case that the fifthinformation for the first downlink component carrier corresponding tothe first bandwidth class of the first band in the first bandcombination is not configured, a fifth maximum number of the layersassumed for determining a bit width for the RI is given by referring toany one of the first information and the third information, and in acase that the fifth information for the first downlink component carriercorresponding to the first bandwidth class of the first band in thefirst band combination is configured, the fifth maximum number of thelayers assumed for determining the bit width for the RI is given byreferring to the fifth information.
 14. A communication method used fora base station device, the method comprising the steps of: receiving,from a terminal device, a Rank Indicator (RI) determined by the terminaldevice, the RI corresponding to a number of useful layers andcorresponding to Physical Downlink Shared CHannel (PDSCH) transmissionin a first downlink component carrier corresponding to a first bandwidthclass of a first band in a first band combination; transmitting thePDSCH to the terminal device; receiving, from the terminal device,capability information including first information, second information,and/or third information; and transmitting, to the terminal device,fifth information for the first downlink component carrier correspondingto the first bandwidth class of the first band in the first bandcombination, wherein the first information indicates a UE categorycorresponding to a first maximum number of the layers supported by theterminal device in a downlink, the second information indicates thefirst bandwidth class being for the first band in the first bandcombination and corresponding to a number of downlink component carrierssupported by the terminal device, the third information is applied toall of one or more downlink component carriers corresponding to thefirst bandwidth class of the first band in the first band combination,and indicates a second maximum number of the layers supported by theterminal device in the downlink, the fifth information indicates afourth maximum number of the layers, in a case that the fifthinformation for the first downlink component carrier corresponding tothe first bandwidth class of the first band in the first bandcombination is not configured for the terminal device, a fifth maximumnumber of the layers assumed for determining a bit width for the RI isgiven by referring to any one of the first information and the thirdinformation, and in a case that the fifth information for the firstdownlink component carrier corresponding to the first bandwidth class ofthe first band in the first band combination is configured for theterminal device, the fifth maximum number of the layers assumed fordetermining the bit width for the RI is given by referring to the fifthinformation.